Mix '07's sleeper announcement: Cross-platform CLR

I agree with my ZDNet blogging colleague Ryan Stewart. The biggest Mix '07 announcement made on opening day of this week's show was one that Microsoft didn't call out in any of its own press releases: Microsoft is making a version of its Common Language Runtime (CLR) available cross-platform.

The CLR is the heart of Microsoft's .Net Framework programming model. So, by association, the .Net Framework isn't just for Windows any more.

Silverlight 1.1, an alpha version of which Microsoft has made available for download, includes a very slimmed down version of the CLR, plus the newly announced Dynamic Language Runtime (DLR). Silverlight will plug into Internet Explorer, Mozilla and Safari browsers, meaning the slimmed-down CLR will run on these platforms, as well.

Microsoft calls the streamlined CLR the "Core CLR." (The Core CLR's codename was Tolesto, which happens to be one of the moons revolving around Saturn, according to the Softies.) The Core CLR will include the garbbage collection, type system, generics and many of the other key features that are part of the CLR on the desktop. It won't include COM interop support and other features "that you don't need inside a browser," the Microsoft execs say.

Microsoft is not opening up the source code to the Core CLR. It is opening the code to the DLR by posting it to the Microsoft CodePlex source-code repository under a Shared Source Permissive license.

Any non-Microsoft developersout there keen on seeing the CLR go cross-platform?