Some Japanese sites and some mac sites are reporting that at the Power Everywhere Forum 2005 IBM has announced official details on the PowerPC 970MO processor.
The specs appear on the slide below but I'll list them here:
970MP
Dual Core
1.4-2.5Ghz
Each core has 1MB L2 Cache
One core can be switched off for low power mode
Low Power 970FX processor specs:
1.2Ghz at 13W
1.4Ghz at 13W
1.6Ghz at 16W
It is expected that some future Macs will included these chips before the final switch to the Intel base.
Going out on a limb I'd assume these may go into the portable line to help sales.
Image not in archive — IBM Presentation Slide showing 970MP Specs