Compiz fusion is the name that of the recently merged Compiz and Beryl projects (Beryl was a fork of Compiz) and it all got very complicated but they have agreed to bury the hatchets and work together again 
which is good news, anyway I got sent this YouTube clip the other day which is a demo of some of the new stuff they are working on
http://www.youtube.com/watch?v=E4Fbk52Mk1w
Pretty snazzy stuff, I am merely running vanilla compiz here at the moment, but apparently the next version of Ubuntu in the autumn will have Compiz Fusion instead