"Pixel Bender" (originally Hydra) is the official name for Adobe's new scripting language for writing fast imaging filters. The same technology is already being used to power some filters in After Effects CS3, and we can expect more throughout Adobe applications in time. For instance, according to John Nack, "an AE plug-in developer could effectively also develop runtime effects for Flash, while a Flash developer could leverage her work inside AE."
Pixel Bender will be tough going for most of us, but mere mortals can get a peek. Lee Brimelow posted 2 video tutorials on getting started with Pixel Bender and using the filters in Flash on his site gotoandlearn.com.
You also can check out an online demo app and download the Pixel Bender Toolkit from Adobe Labs.
-via Kevin Goldsmith's blog
Update: John Nack posted some notes (9/21/08) on Photoshop and Flash in New Pixel Bender hotness.