Catfish_Man submitted this last night - IBM's latest G3 processor (Oct, 2001) which is the most likely chip in the upcoming iMacs:
Manufactured in IBM's advanced 0.13 micron copper process with Silicon-on-Insulator and Low-K Dielectric technology, the 750FX will be offered at frequencies up to 1 GHz.
Though the article states it would only begin "sampling" in Jan 2002.