I have read that yesterday Adobe added GPU acceleration support for Flash playback of MP4 (H.264). However, based solely on Google results it appears that this only affects Macintosh users. Was this hardware acceleration feature already existent in Flash for Windows? And furthermore, has anyone noticed increased performance, especially for Hulu, youtube, etc?
Theres a possibility you might have missed the tone of whoever wrote "this will only affect macintosh users". It could have been a satirical swipe at macs and their low processing power making youtube and related players sluggish. Putting the work onto a mac's GPU would accelerate the process to a smoothness that us PC users get purely off our CPU's (oh those poor mac children).
Anyway, if adobe are going to dd support for any one platform it will be Windows since Apple have spat their dummy out at Adobe and Flash and aren't supporting it anymore in the iPhone and iPhad.
Generally, modern PC's running Windows won't need GPU acceleration for flash video players unless you've got an old machine that's trying to play a monkey picking its own arse and smelling it on Youtube in 1080P (a magical experience).