If you go to the media pool, there's a small "broom" there that will remove any unused clips from the project.
If you do a File-Save As, specify a new folder, and check the "Copy and trim media with project", it will save only the pieces of the clips that are in use.
In either case, if the desire is to clear up disk space you would then have to manually delete the files from your hard drive.
Ok. Does "Save As" Copy the actual media as well?
Then I would just have to delete the old, unused media folder?
If so - its the same as "Copy project" in FCP -- which is what I use anyway.
It's the same, except that in FCP 4, you can also delete sections of media unused while the project is open. In Vegas, you sweep the media pool to make sure unused stuff isn't in the project, then save, and it copies the USED portions of clips. It allows you to set a head/tail as well, so you've got the option for pre/post roll in Vegas. Then delete the old media folder.
In FCP 4 I've had issues with the MM shifting my I/O's -- it totally screwed up a project for me, and I deleted the old project before I caught on.
Any issues at all with the Vegas version?
There is one issue that disturbs some folks. Your AVI clips will be split into two separate files: a new silent AVI file containing the video only, and a new W64 file containing the audio. Generally this doesn't cause any problems as long as you stay within Vegas or other SONY Media software. It can confuse you if you're not expecting it though, and it makes the clips relatively unusable in other software because only SONY's software opens W64 files.