Adobe has announced that the next version of the software will run on 64-bit Operating Systems only. It's not all the apps in their suite, but the apps that will most benefit.
"It’s common knowledge among post-production pros that 64-bit operating systems are the best choice for top-of-the-line performance, especially when producing HD or higher-resolution content. After 3 versions of simultaneous 64 bit and 32 bit support for After Effects and Premiere Pro, we wanted to let you know today that CS4 will be the last version of Adobe’s leading video applications to support 32 bit operating systems."
Simon Hayhurst – The Senior Director of Product Management for Dynamic Media
Check out the news here.