> I can't remember where I saw the 3.0 Ghz quote

It was e700 that was said to go up "to 3 GHz and beyond" when announced in 2004. Maybe you got confused by all these numbers? ;-)

> then 2.5 Ghz. Twice the speed of the MPC8641!

2.5 GHz is twice the clock of the MPC8640. Twice the clock of the MPC8641 would be 3.0 GHz :-)