Whether is builds or not is unimportant, the apple changes to work with Apple's flavor of Obj-C (Cocoa), frameworks, PPC optimization (such as they are) the dynamic loader, etc.. are not included in gcc 3.0, but they are in the works for 3.1. Stan Shebs over at Apple is working on this, and you can get the current state of this project on the Darwin CVS, but it is not ready for prime time... (as in sometimes doesn't even bootstrap)