The way I understand (correct me if I am wrong) is that Perforce’s value add with features like this is what makes it sticky. So from my gut they will have some patents on this.

But that said, I had once used http://code.google.com/p/svn-time-lapse-view/

The experience wasn’t usable at all since there was no caching, prefetching etc. Each move of the slider resulted in a web request.

But git is a different story …. :-)