Let's look at iphone 3GS's biggest rival, HTC Hero, which runs flash. Not surprisingly, it sucked on there, just like in every other mobile devices. I've never been a fan of flash, and I personally try to avoid any flash heavy website. Because they kick up my laptop's fan for no good reason, and is mostly unresponsive. Flash needs to die or seriously improve on performance. Hopefully GPU utilization would help this situation.