We're pleased to announce that Premiere Pro CS5 is now publicly available for download, both as a 30-day trial and for purchase:
http://www.adobe.com/go/trypremiere_pro
In addition, the Premiere Pro CS5 SDK is now publicly available:
http://www.adobe.com/devnet/premiere/
We're excited to see all the plug-ins and tools that you developers create to extend the capabilities of CS5! Happy coding.