Windows/Mac/Linux: Adobe is offering up a "prerelease" of its inescapable Flash software, adding in GPU acceleration for H.264 video in Windows, multitouch support and bug fixes. Anyone with Adobe AIR apps can also grab a 2.0 prerelease of that platform.
Yes, you read right — only Windows gets the graphics-card-powered HD acceleration for now. Even though that matches up nicely with YouTube's expected 1080p HD roll-out, it's a shame that Mac and Linux users get left out in the wilds of jerky video. All platforms get support for multitouch, however, and tweaks that presumably make Flash a tad bit less of a resource hog.
Adobe AIR 2.0 beta, meanwhile, adds in a whole bunch of native computer functionality, including USB access, better networking compatibility, the ability to open a link or file with its native application (making awkward TweetDeck hacks less necessary), and a faster native WebKit browser, among other improvements.
Both Flash 10.1 prerelease and AIR 2.0 beta are free downloads for Windows, Mac and Linux systems. Tell us what you're seeing improved, or broken, by the new releases in the comments.