C# is so un-Microsoft in a lot of ways that it is spooky. It works great, looks good and does what people want. With the 3.0 (numbering is hard) version they are moving the language ahead a big deal in providing language level support for common programming tasks.
And with the Mono open source implementation it is essentially more salonfähig than Java is in the open source world.
I like what the Mono guys are doing but I still feel that they are more helping Microsoft people achieve their platform dominance than taking away their market share.
For most of my work I will stay with Python and that is also being greatly helped by the rapidly maturing IronPython project. It's nice to see that their implementation is getting faster and faster.