Thanks to Andreas_Wolf for pointing (ok, linking :)) me to coreplayer for OSX.

This player is awesome, plays 720p movies (even my 4 gig ones), perfectly. I believe it is altivec optimized.

While your waiting for 3.0 on the PB, give this a try:
Coreplayer

It isn't free, but for $20 bucks it makes the pb useful... The only downside is that is doesn't play a variety of formats. I have been using it for mk4...