Wired: IBM Promises Muscle for the Mac:

The chip promises to goose Macintosh clock speeds, which right now trail Intel's Pentium line significantly. Pete Sampson, IBM senior PowerPC architect, says that the PowerPC 970 will reach clock speeds of 1.8 GHz and will also be able to do a lot more with each processor cycle. Current G4 CPUs can issue three instructions per cycle; the PowerPC 970 will issue eight.

Supposed to come out late 2003. I guess the rumoured move to Intel is forcing a bit of a fightback on the PowerPC side.