Click here or on the image below for an overview of Visual Studio 2010 and .NET Framework 4.0. I heard rumors that a pre-Beta CTP was externally available for download, perhaps via Microsoft Connect. I'll won't get to use it anyway because my team uses Source Insight. Don't read anything into that though! Visual Studio is the tool of choice for working with .NET and Team System. The application lifecycle tools in VSTS 2010 look really good!
[11-4-2008: The rumors are true. You can access the CTP on Microsoft Connect.]