kwajo.com said:the G3 had better be supported by Leopard, I have a G3 iBook 900MHz that can run circles around my early G4 Powermac, so logically you'd think it would handle Leopard better as well. The system is from late 2003, so less than 3 years ago, which is well within the usual time frame of system support for Apple, and still under Applecare no less.
But Leopard is not out yet. Assuming it ships in early 2007 your machine will be over 3 years old and outside Applecare. I'd not bet on G3 support in Leopard.
Edit to add: If the G4 is not supported in 10.6 then it might make sense to remove G5 support as well. If Apple are going to have any PPC architecture support they might well retain the G4 support.