As a response to Wilson Miner above, I'm a huge fan of Subversion which will also does binary files well (not like CVS where I cringed every time I checked in a binary wondering if I'd ever be able to see it again)

Merging is still a problem though.

http://en.wikipedia.org/wiki/Subversion_%28software%29

Great article Rands, I'm all about the required commit notes.