I FINALLY got ProjectBuilder to work with CVS.
This means my PerlCulator/YAPC (Yet Another Perl Calculator) and my Games Bingo OSX applications developed with CamelBones can be put under revision control.
Check out these links:
http://developer.apple.com/qa/qa2001/qa1245.html
http://www.heathmoor.plus.com/will/cvs.html