MiguelĘde Icaza is talking on Beyond .NET: The Mono Project. Mono is a virtual machine, a set of class libraries, and development tools for an open source version of C#. The project is two years old. Miguel is an entertaining speaker.
Dan Olsen and I have had some Java vs. C# discussions. Dan is sold on C#, I've primarily been stopped by two things: (1) I need a bigger difference than the one that exists between java and C# to learn another language and (2) I'm not happy to be locked into a Microsoft environment---in fact I'll avoid it at almost any cost. Miguel says that C# is a decent language. Better than that, Miguel says that the runtime engine (CIL) makes it a language that will last. Even if he wants to change languages later, the runtime engine ensures that the C# he writes now will be useful with anything that runs on that runtime. With an open source runtime, that's a real advantage.