No, there is no typo in the title of this post – there is a .NET "Micro" Framework (which is a Microsoft stack in case you were wondering). I had not heard of such a thing until today (but then I have not done any embedded stuff for a while).
It is designed to use only a few hundred kilobytes of RAM (512K) and an inexpensive processor (ARM7 and ARM9 based). In addition to the usual managed code advantages (GC, exception handling, etc.) it also supports standard interface such as SPI, I2C, (Serial) GPIO and USART. You can download the SDK and use it with VS 2005 (or higher) and of course get all the productivity gains of the IDE.
There is also support for Flash-based devices with tools allowing you to "re-flash" and there are a number of developer kits such as Digi Connect for Ethernet networking solutions, EmbeddedFusion Tahoe which works with a Meridan CPU and Freescale i.MXS which allows you to build SideShow apps – they are not cheap mind you.
Basically this gives you another choice when working on an embedded platform. The various pros and cons of the three options available i.e. .NET Micro Framework, Windows CE, Windows XPe (that is XP Embedded) are outlined here – interestingly Microsoft Robotics Studio is not featured in that comparison.
Now the challenge will be to get some time to sink my teeth in this.