If I'm reading right, it appears Microsoft is going to have an out-of-browser .NET runtime for the Mac based on something to be packaged with Windows Presentation Foundation/Everywhere, the upcoming cross-platform browser-based user interface technology for the .NET 3.0 development framework. WPF/E already promises stripped down .NET programming inside a browser across multiple platforms. To me this news means expanding C# programming to the Mac and giving Microsoft developers the capability to build cross-platform smart client apps. Ray Winninger (who's helping run MIX) recently said there'd be "more Macintoshes on stage as part of our keynote presentations than you've ever seen from Microsoft before."
The source I spoke with today said the news would "shock the world" and that it's something Microsoft said it would never do because of concerns about the Department of Justice. I don't know about that, but if this is correct, it would certainly expand the horizons of developers.
Hold up, Mac enthusiasts may say. This is something the open source Mono already does, creating a way to make C# and .NET programs available for the Mac. Yes, but the technology Guthrie mentions would be based on a small common language runtime version of the .NET framework, much tinier than the whole framework. It would be something that could conceivably be extended elsewhere. Would a mobile version be next?
However, there are a few things that leave me scratching my head. I was also told (by the same aforementioned source) that some of the commenters to a Mary Jo Foley blog post have gotten close to figuring this news out, but the commenters on the most likely thread are barely dancing around somthing like managed code for the Mac. Plus, a Microsoft spokesperson directly connected with public relations for MIX, whom I spoke with today, said she didn't know what I was talking about. And isn't MIX supposed to be about Web development? I guess smart clients fit right in, but...
Maybe (probably?) this is not the big news. And though interesting and market expanding, it doesn't exactly scream "shocks the world" in my mind. Does it to you? Could I be barking up the wrong tree? Is the Mac involved at all? I guess we'll find out fairly soon.