On a VSLive webcast, Pablo Castro has published this interesting slide, that shows how Microsoft handles the releases of the last .NET technologies:
This slide shows clearly that .NET 3.0 is something like a (big) addon to .NET 2.0: the development platform will be the same as today (Visual Studio 2005) but with the add-in of all the interesting new technologies such as WCF, WPF and Windows Workflow (that fascinates me a lot 
).
Thanks to Sahil for the slide...