Well, I've got the basic backup script done--another surprisingly easy task. Linux's Logical Volume Manager supports the creation of snapshots quickly and cheaply, so all I needed to do was create a snapshot and backup onto another vlume. To accomplish this, I used rdiff-backup. Rdiff-backup is a differential backup solution that supports versioning, just like Time Machine does. All the core backup script required was a short 10-line script and a daily cron job. It will automatically run once daily, and will delete file revisions older than 4 weeks. Unlike Time Machine, this can backup any arbitrary location to any arbitrary volume--external devices are not required, though they would be supported. However, I have not yet completed the GUI for this. If anyone has any suggestions for things they'd like to see, I'm all ears. Currently, all I've got in mind is a small dialog that lets a user select a particular file or directory, and (optionally) a previous revision, then lets them restore it.

How about UI for comparing or viewing the actual contents of the revision?

When I first heard this idea, I also thought it was a good one. But then I got to thinking about it. Other than for plaintext, when would this ever be needed? A diff on a binary file usually doesn't give much in the way of human-readable output. I mean, sure, you can detect a change, but that's about the only user-friendly result you're going to get. Perhaps I simply misunderstand the request--do you just want file previews or something?

Well, I think we're both talking about the same idea. Maybe file previews can assist with the implementation of the idea.

I finally got around to completing this--it's been a busy week. Anyway, I did decide to add revision previewing to this--as such it can preview past revisions of any kind of file which is supported by Konqueror (plaintext documents, word documents, videos, images, etc). It can also restore from any of these previous revisions. Unfortunately, this is not searchable at present--you need to know the name and path of the file you're looking for in order to preview or restore.

Given the trouble that people were having previously with Theora, I've also made a low resolution XviD video available.
TARDIS Video Demo (Ogg Theora, 1440 x 896)
TARDIS Video Demo (XviD, 640x480)

What are you using to do the screen recording?

recordmydesktop Specifically, gtk-recordmydesktop. Are there problems with the video again?

No, they work fine. I want in on the desktop recording.

Edit: It works!