A couple of people have started talking about the .NET Micro Framework which is, as the name suggests, an extremely cut down version of the .NET Framework. Unlike the .NET Compact Framework which was designed to run on top of an existing OS, the .NET Micro Framework can operate without an underlying OS. As such it has provisions for a HAL that is specific to the device onto which it is to be run. The best news is that this is all going to have rich developer support through Visual Studio. Check out the new whitepaper that provides early information about this framework.
.NET Micro Framework Whitepaper