This release represents the beta of Microsoft XNA Game Studio 3.0, which enables hobbyists, academics, and independent game developers to easily create video games for Windows and the Microsoft Zune digital media player using optimized cross-platform gaming libraries based on the .NET Framework.
The XNA Game Studio 3.0 Beta is a chance to get an early look at XNA Game Studio 3.0, and provide feedback on the product that is currently in development.
Now it supports Zune with the 3.0 software version. The CTP version didn’t have support for XBOX 360 development, now it is fully supported 
Finally we can use Visual Studio 2008 for XBOX 360 development! Other features that please me are the Rich Presence support (that message in XBox Live that tells you what are your friends playing in the context of a game. eg: level, dificulty,etc.), and Invites for joining you in a multiplayer game.
sweet