Adobe Flash 11 brings 64-bit support, NVidia VDPAU and Broadcom Crystal HD acceleration and a variety of of technical features for web developers and flash programmers to take advantage of.
Download links for both the 32bit and 64bit versions of this release can be found at labs.adobe.com/downloads/flashplayer11. Do bear in mind that this is a release candidate and not a stable build, so usual warnings about non-stable software apply.
64bit Ubuntu 8.04, 9.10, 10.04, 10.10, 11.04 and 11.10 users are also able to upgrade/install using the unofficial Flash PPA maintained by SevenMachine.
Add ppa:sevenmachines/flash to your Software Sources. Don’t know how to do that? See here.