This year I was allowed to visit //build in Anaheim California to experience first hand whats coming to Windows 8 next year ( www.buildwindows.com).
And it was alot to learn there - hundreds of sessions to visit (they are on channel9 right now to download). Windows 8 will have a cool new API named Windows Runtime (aka WinRT). Based on a COM-like layer you will be able to access it via C++/C#/VB.Net and HTML5/JS. Nice because the GUI part is funded on XAML - but in a native, and vastly optimized way.
So far its rather unfinished work - its a Developer Preview - not even Beta quality. But keep in mind - if you like to profit from the soon to be released Store and the new possibilities for writing Metro style apps - you need to learn the new API...
Desktop apps won't profit from this new layer unfortunately. On the other hand - .Net will be updated again to .Net 4.5/C# 5.0 with some nice new features. A developer preview of VS 2011 is also available to experiment with.
All after all - really much exitement of the things Microsoft has done with Win8 and many new stuff to learn - fun times.