The Service Pack1 Beta is available for the .NET Framework 3.5 and Visual Studio 2008. The SP1 comes with new features.

Lets have look here for features and download:

Microsoft .NET Framework 3.5
Service pack 1 Beta

Microsoft Visual Studio 2008 Service Pack 1 Beta

Here is the complete list of features to choose your platform.

Compare Windows 2008 and Red Hat

Besides having wonderful looks and features to attract hobbysists and PC users. Windows Vista have many new fearures to attract the developers too.

Lets find out here:
What’s New in Windows Vista for Developers