Here's a really, really old one: SlideshowToMarkers2.js (I didn't write this one and it will take some updates to run in current versions of VEGAS. This one was for Vegas 4. I start by changing import SonicFoundry.Vegas; from "SonicFoundry" to "ScriptPortal". It would probably run after that.

// Assuming there is an audio track with appropriate number of numbered and
// unnumbered markers, and a bin in Media Pool with images, automate image
// sequence to timeline at markers. Apply default transition/dissolve in the
// process.
// Maybe pick images from directory in future versions.

import System.Windows.Forms;
import SonicFoundry.Vegas;
import Microsoft.Win32;

// This is for convenience in comparison and assignment.
var zeroMark = new Timecode(0);
// These are default values for parameters in a dialog.
// Half-time of dissolve. Half because we add it to both dissolving clips.
var overlap: Timecode;
// Region that is subject to script. By default it is entire project.
var begin: Timecode, end: Timecode;
// Default name for bin holding our slides.
var binName;
// 0 - entire project, 1 - from cursor to the end of project, 2 - loop region.
var regionType;

try {
  // Last snapshot file name is stored in Windows registry.
  var regKey = Registry.CurrentUser.CreateSubKey("Software\\Sonic Foundry\\Scripts\\SlideshowToMarkers");
  binName = regKey.GetValue("Bin name", "Slides");
  overlap = new Timecode(regKey.GetValue("Overlap", "00:00:01:29")); // Approximately 2 seconds.
  regionType = regKey.GetValue("Region", 1);

  var dialog = new SlideshowDialog(binName, overlap, regionType);
  var dialogResult = dialog.ShowDialog();

  // if the OK button was pressed...
  if (System.Windows.Forms.DialogResult.OK == dialogResult) {
    binName = dialog.binNameBox.Text;
    overlap = new Timecode(dialog.overlapBox.Text);
    regionType = dialog.regionBox.SelectedIndex;
    switch (regionType) {
      case 0: begin = zeroMark; end = Vegas.Project.Length; break;
      // If there's no selection then SelectionLength is 0 (zero).
      case 2: begin = Vegas.SelectionStart; end = begin + Vegas.SelectionLength; break;
      default: begin = Vegas.Cursor; end = Vegas.Project.Length;
    }
    // Write settings back to Registry.
    regKey.SetValue("Bin name", binName);
    regKey.SetValue("Overlap", overlap.ToString());
    regKey.SetValue("Region", regionType);

    // If event is shorter than this then its all just transition.
    // That will look bad aestethically.
    var threshold = overlap + overlap;

    // Although it is called audio track here, it does not matter, since markers
    // are global to progect and there is nothing specific to audio track that
    // we use below.
    var audioTrack = FindSelectedTrack();
    // Hardcoded name of the new track.
    var videoTrack = new VideoTrack(audioTrack.DisplayIndex, "Slideshow");
    Vegas.Project.Tracks.Add(videoTrack);

    var mrkEnum = new Enumerator(Vegas.Project.Markers);
    // Two variables to identify start and end of created event.
    var prevMark: Timecode = begin, currMark: Timecode = begin;

    // Find the bin containing slides.
    var bin = FindMediaBin(Vegas.Project.MediaPool.RootMediaBin, binName);
    if (bin == null) {
      MessageBox.Show("Could not find '" + binName + "' bin in Media Pool.");
    } else {
      // Position on first image in the bin.
      var imgEnum = new Enumerator(bin);

      // Smart code below is to advance currMark until the length of event will
      // be greater than threshold. Then subsequent slide is put on the timeline
      // thus creating an event.
      while (!mrkEnum.atEnd()) {
        currMark = Marker(mrkEnum.item()).Position;
        if ((currMark > begin) && ((currMark - prevMark) > threshold)) {
          PlaceImageOnTimeline(imgEnum, prevMark, currMark);
          prevMark = currMark;
        }
        if (currMark >= end) break; // To avoid extra looping after we reach end of processing region.
        mrkEnum.moveNext();
      }
      // The last marker may not mark the end of processing region.
      // This special case is handled by code below. Notice that we compare to
      // overlap here because for the last event dissolve is applied on one side
      // only. Would be good to handle the first event in similar way ...
      currMark = end;
      if ((currMark - prevMark) > overlap) {
        PlaceImageOnTimeline(imgEnum, prevMark, currMark);
      }
    }
  }
} catch (e) {
  MessageBox.Show(e);
}

// Retrieve the next available image and create event on timeline.
function PlaceImageOnTimeline(images: Enumerator, from: Timecode, to: Timecode): void {
  // Advance to next image.
  var imgStream: MediaStream = FindNextImage(images);
  if (imgStream == null)
    return;
  // Add handles for dissolve. Transition is centered on marker.
  // Keep timecodes withing the range of audio track.
  from -= overlap;
  if (from < begin) from = begin;
  to += overlap;
  if (to > end) to = end;
  // Create the new video event and add it to the track.
  var evnt = new VideoEvent(from, to - from);
  videoTrack.Events.Add(evnt);
  // Create a new take using the video stream.
  var takeName = null;
  evnt.Takes.Add(new Take(imgStream, true, takeName));
}

// Walk the bin tree recursively until the 'name' is found.
// If several bins on different levels have the same name, first one will be
// returned.
function FindMediaBin(parent: MediaBin, name: String): MediaBin {
  if (String.Compare(parent.Name, name) == 0) {
    return parent;
  }
  var binEnum = new Enumerator(parent);
  while (!binEnum.atEnd()) {
    var abin = binEnum.item();
    if ((abin instanceof MediaBin) && (abin.Name != parent.Name)) {
      // Recurse here.
      abin = FindMediaBin(abin, name);
      if (abin != null)
        return abin;
    }
    binEnum.moveNext();
  }
  return null;
}

// Get next available media as video stream. There is no check if this is
// slide/image. Any media containing video is acceptable.
function FindNextImage(mediaEnum: Enumerator): MediaStream {
  while (!mediaEnum.atEnd()) {
    var img = mediaEnum.item();
    mediaEnum.moveNext();
    if ((img instanceof Media) && Media(img).HasVideo()) {
      return img.Streams.GetItemByMediaType(MediaType.Video, 0);
    }
  }
  return null;
}

function FindSelectedTrack() : Track {
  var trackEnum = new Enumerator(Vegas.Project.Tracks);
  while (!trackEnum.atEnd()) {
    var track : Track = Track(trackEnum.item());
    if (track.Selected) {
      return track;
    }
    trackEnum.moveNext();
  }
  return null;
}


// Form subclass that is the dialog box for this script
class SlideshowDialog extends Form {
  var binNameBox;
  var overlapBox;
  var regionBox;

  function SlideshowDialog(binName, overlap, region) {

    this.Text = "Create Slideshow";
    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
    this.MaximizeBox = false;
    this.StartPosition = FormStartPosition.CenterScreen;
    this.Width = 300;

    var buttonWidth = 80;

    binNameBox = addTextControl("Bin Name", 10, 200, 10, binName);
    overlapBox = addTextControl("Overlap Time", 10, 140, binNameBox.Bottom + 16, overlap.ToString());

    var label = new Label();
    label.AutoSize = true;
    label.Text = "Region:";
    label.Left = 10;
    label.Top = overlapBox.Bottom + 20;
    Controls.Add(label);
    regionBox = new ComboBox();
    regionBox.DropDownWidth = 100;
    regionBox.Left = label.Right;
    regionBox.Top = overlapBox.Bottom + 16;
    regionBox.Items.Add("Entire Timeline");
    regionBox.Items.Add("From Cursor");
    regionBox.Items.Add("Loop Region");
    regionBox.SelectedIndex = region;
    Controls.Add(regionBox);

    var buttonTop = regionBox.Bottom + 16;

    var okButton = new Button();
    okButton.Text = "OK";
    okButton.Left = this.Width - (2*(buttonWidth+10));
    okButton.Top = buttonTop;
    okButton.Width = buttonWidth;
    okButton.Height = okButton.Font.Height + 12;
    okButton.DialogResult = System.Windows.Forms.DialogResult.OK;
    AcceptButton = okButton;
    Controls.Add(okButton);

    var cancelButton = new Button();
    cancelButton.Text = "Cancel";
    cancelButton.Left = this.Width - (1*(buttonWidth+10));
    cancelButton.Top = buttonTop;
    cancelButton.Height = cancelButton.Font.Height + 12;
    cancelButton.DialogResult = System.Windows.Forms.DialogResult.Cancel;
    CancelButton = cancelButton;
    Controls.Add(cancelButton);

    var titleHeight = this.Height - this.ClientSize.Height;
    this.Height = titleHeight + okButton.Bottom + 8;
  }

  function addTextControl(labelName, left, width, top, defaultValue) {
    var label = new Label();
    label.AutoSize = true;
    label.Text = labelName + ":";
    label.Left = left;
    label.Top = top + 4;
    Controls.Add(label);

    var textbox = new TextBox();
    textbox.Multiline = false;
    textbox.Left = label.Right;
    textbox.Top = top;
    textbox.Width = width - (label.Width);
    textbox.Text = defaultValue;
    Controls.Add(textbox);

    return textbox;
  }

}