Raphael Simon and Emmanuel Stapf, the Eiffel developers, have an article on MSDN. Its an updated version of an earlier article and describes the current state of Eiffel for .NET - which they claim supports the full language.
The article describes support for MI using interfaces. It sounds a bit of a hack and it will be interesting to see how it works in practice.
I had a brief flirtation with Eiffel a few years ago. I learnt the language, wrote a fair amount of code, and even applied for one of the few Eiffel jobs in the UK. I was offered the job but it turned out the salary was considerably less than what I was already earning and there were subtantially higher commuting costs so unfortunately I couldn't take the job.
Maybe the best thing for Eiffel would be for Microsoft to buy Meyer's company, now called Eiffel Software Inc, or at least sell the .NET version of Eiffel. Its a great language and this might be compromised with MS involvement, but without big company support it may always remain in its niche. If Microsoft were selling the product IT managers would have confidence that it was going to be around for a long time. On the other hand maybe .NET integration is sufficient to bring the language into the mainstream. "Envision", the Visual Studio plug-in to be released soon, is going to cost $499 with an introductory offer at $299.