.NET Micro Framework

http://msdn.microsoft.com/en-us/netframework/bb267253.aspx

The .NET Micro Framework is an innovative development and execution environment for resource-constrained devices . The typical .NET Micro Framework device has a 32 bit processor with no external memory management unit (MMU) and could have as little as 64K of random-access memory (RAM).

In addition it is useful to visit the .NET Micro Framework MSDN page. There you will find the SDK, White Papers, tutorial videos and various other useful items.
http://msdn.microsoft.com/en-ca/netframework/bb267253.aspx