EiffelLanguage has an ObjectModel fairly different from the MicrosoftCorporation CommonLanguageRuntime.
This article explains how Eiffel gets around the differences to add such significant features as multiple inheritance which are not supported by .net's CLR: http://www.devx.com/codemag/Article/8500/0/page/1
Eiffel (Oct. 2002) offers something called ENViSioN! (non-Wikiable if ever there was a non-Wikiable name) which is an plugin for Microsoft's Visual Studio that allows development in the Eiffel language. There's even a free version for non-commercial use: http://www.eiffel.com/products/envsn10/FeatureComparison-ENViSioN10.pdf
The language name is now simply EiffelForDotNet? (without the #).
Previously...
Eiffel# is a version of the EiffelLanguage designed specifically for the MicrosoftDotNet platform. See the following URL for an overview of the language and its differences from the EiffelLanguage:
The name was changed from Eiffel# to EiffelForDotNet? as the first implementation (Eiffel#) was a subset of real Eiffel and as such a different language. Now that they managed to map all Eiffel constructs to the CLR, they call it EiffelForDotNet?.
See also: MicrosoftDotNet CommonLanguageRuntime