A fortuitous incident led me to review the .NET Languages website, which has a great list of .NET languages on its Resources page. There, I found out about a new-to-me compiler, #Smalltalk, that implements Smalltalk to run on .NET. The #Smalltalk system is offered under an Open Software License version 1.1 and the included class library is supposedly "mostly compatible with the ANSI Smalltalk standard." In its current version, #Smalltalk does not have support for GUI development but such is planned for a future release.