Because Rudy is a pro-choice Northeastern Republican, he would likely pick a southern, more conservative, pro-lifer for VP, in order to balance the ticket. This probably rules Condi out.

On the other hand, if it's McCain in 08, since he's a southwesterner and pro-life, I could see him more readily having Condi as VP.

The other problem for Condi is that, frankly, while she's a brilliant person, she's not really a politician and has never run, to my knowledge, for anything. In this day and age, you don't get to be President (or Vice President) without a few campaigns under your belt.