I've been playing NCAA Football '08 and you can challenge plays. Unless I'm mistaken, there was no instant replay last season, correct? & Are they going to have it this year?

Each conference has their own rules on replay. Some have been doing it for 3 years.

Yes, that started last year.

And on another note, what is up with NCAA 08 previewing all of that cool new dynasty features, play with the prospect, new jersys for teams, and I have a PS2 and it had NONE OF IT. I don care if it has it or not, just when you preview say FOR XBOX 360 ONLY!

Yes, The NCAA uses instant replay. They started last year as a result of the officiating debacle in the USC vs Texas Rose Bowl game.