I just wrote a script to dump all my perforce changelists from the server to my local drive.
And I'm running Google Desktop, so it indexes them all instantly. The trick is to put them all in a folder with a special name (like "changelists") and then search your desktop for "changelists picasa" or whatever you want to find. Makes a total history of who did what and when and why.
I've always wanted source code history & searchability (like a wiki at least), and this gets me lots of the way there.