I just orderd one of these from Outpost.com: 1GB SODIMM I received it yesterday, popped it into my iBook G4, and it works great. 1.128GB in my iBook! I think this same chip would work in at least the new PB G4s as well. Crucial wants almost the same money for the 512MB chip. Your mileage may vary, but I'm a very happy camper.