I just opened up my new 21.5" iMac w/ Nvidia about an hour ago. Shipped with 10.6.1 and used Software Update to update everything including the performance patch.
Without installing any programs whatsoever, and also not transferring data from my old Mac, I went directly to YouTube to test it out. Watched a trailer for Invictus in HD. Video lagged similar to the video MR used for this news topic and processor consistently ran at ~66% and spiked to 85% at one point.
Everything on this computer is what Apple preinstalled and it can't even play an HD trailer smoothly.
Regardless of the BS reasons anybody can think of to deflect blame solely on Adobe, this is simply unacceptable.