No doubt many of you have heard that Silverlight 2 RC0 just debuted. There's loads of bug fixes here since Silverlight 2 Beta 2 and some breaking changes as well. Unlike the breaking changes document from Beta 1 to Beta 2 (which was 80 odd pages) this one's only about 20 pages. To be honest, I don't think it's going to be very much work going from SL2B2 to SL2RC0. Go here for the breaking changes document and here for the release. The tools are meant for Visual Studio 2008 SP1 so make sure you upgrade to that before installing.
There's also a corresponding version of Expression Blend that came out to support this release. Get Expression Blend 2 Service Pack 1 Preview here.
Let there be light indeed! :)
Word of caution though. This version is not intended for releasing applications on, only to help update your applications to work with the eventual Silverlight 2 release.