Based on the Image sequence script from SonicFoundry, I wrote this small script to export a still image from the cursot position. Save it as a file with a .js extenstion. It saves the images in the root directory of C:, but you can easily change it.

//-------- Start Here -------------

import System;
import System.Text;
import System.IO;
import System.Drawing;
import System.Windows.Forms;
import SonicFoundry.Vegas;


// First save off the preview & project settings that will be set by
// the script so they can be restored when the renders are complete.
var originalPreviewRenderQuality = Vegas.Project.Preview.RenderQuality;
var originalPreviewFillSize = Vegas.Project.Preview.FullSize;
var originalFieldOrder = Vegas.Project.Video.FieldOrder;
var originalProjectDeinterlaceMethod = Vegas.Project.Video.DeinterlaceMethod;
var originalCursor = Vegas.Cursor;
var originalSelectionStart = Vegas.SelectionStart;
var originalSelectionLength = Vegas.SelectionLength;


try {

// Set the preview quality and size.
Vegas.Project.Preview.RenderQuality = VideoRenderQuality.Best;
Vegas.Project.Preview.FullSize = true;

// Set the field order and deinterlace method
Vegas.Project.Video.FieldOrder = VideoFieldOrder.ProgressiveScan;
Vegas.Project.Video.DeinterlaceMethod = VideoDeinterlaceMethod.InterpolateFields;

var imageFormat = ImageFileFormat.JPEG;
var currentTime = Vegas.Cursor;
var nImage = 0
var imageFileName = "c:\\Image00.jpg"
while (File.Exists(imageFileName)) {
nImage += 1;
imageFileName = "c:\\Image" + String.Format("{0:D2}", nImage) + ".jpg";
}
var renderStatus = Vegas.SaveSnapshot(imageFileName, imageFormat, currentTime);

} catch (e) {
MessageBox.Show(e);
}

// restore the project and preview settings
Vegas.Project.Preview.RenderQuality = originalPreviewRenderQuality;
Vegas.Project.Preview.FullSize = originalPreviewFillSize;
Vegas.Project.Video.FieldOrder = originalFieldOrder;
Vegas.Project.Video.DeinterlaceMethod = originalProjectDeinterlaceMethod;
Vegas.Cursor = originalCursor;
Vegas.SelectionStart = originalSelectionStart;
Vegas.SelectionLength = originalSelectionLength;

//-------- End Here -------------