One of the big pieces of news from MIX07 is that Silverlight 1.1 will include the .NET Framework and it will run on Mac OS X in Firefox and Safari. Currently Silverlight also works with IE6, IE7, and Firefox on Windows XP and Vista. Support for Opera is planned but it seems there are too many issues to make it available for public consumption.
In case you’ve missed the previous announcements, Silverlight is the new name for WPF/e, which is Microsoft’s Flash killer (for lack of a better descriptor).
Client-side .NET support is not in the Silverlight 1.0 Beta. It is in the Silverlight 1.1 Alpha release. Silverlight 1.1 uses the same core CLR as the desktop .NET Framework but some things have been factored out. I heard today that COM interop is not included.