This question (http://stackoverflow.com/questions/245566/net-compact-framework-4-0) asked this back before the release of VS 2010. The answer basically said to wait for the release.
Now that the release is here, does anyone know? Is there an upgrade/update to the .NETCF? something past .NETCF 3.5?
Update: You can go here and vote to have Microsoft add this feature.
The Microsoft statement linked in that older answer is still very valid. Studio 10 does not include Smart Device development support. It is supposed to come to us out-of-band, likely when the Windows Phone stuff stabilizes a bit more.
It is no longer supported in Visual Studio (as of the 2010 version), and I doubt it'll ever be. (link)
The new platform for Windows Phone 7 is Silverlight along with XNA for game development (read this for clarification, and this to decide which is the one you should use).
I think they ditched .NET CF (or at least in its previous form) in favor of the aforementioned frameworks.
If you read this description, it is clear that Silverlight in Windows Phone is just a subset of Silverlight for desktop. There are also articles about XNA.
The bottomline is:
It is still good old .NET, but it is no longer the old .NET CF.