The Visual Basic team posted a walkthrough today on some of the new language features in Visual Basic and C# to help with Office programmability in Visual Studio 2010. Specific features include adding optional parameters to C# 4.0 (VB already has this) and removing the dependency on the Primary Interop Assemblies (PIAs).

You can download the CTP and see it in action for yourself and give feedback here.

Enjoy,
-Beth Massi, Visual Studio Community