Looking for backup software that handles revisions

I'm looking for a backup app that basically will back up certain folders I specify, and keep track of revisions. So if I mess up a file, I can dig into the backups and retrieve the copy from 5/20.. or 5/18.. and so on. I know this sounds a bit like Time Machine which will be in Leopard..but.. I can't wait till the fall. SuperDuper is great, but as soon as I clone the main drive, any previous older versions of files are wiped out.

Is there any such thing right now for OS 10.4?