AppleInsider provides some information on IBM's direction with their new G3 processors that were recently announced. They report that the 750CXe should hit Ghz speeds by next year. Of most interest is this quote on whether or not we'll see these chips in Apple hardware in the future:
"According to sources, Apple has now made an unofficial decision to begin to convert the processors in each of its products to the G4 family of processor chips, with the exception of the iBook, by next year. This leaves the next-generation of IBM's G3 processors solely in the hands of third party upgrade card manufacturers, as the 750CX line of chips are not suitable for Apple's plans for the iBook."