Heads up on a possible version number misunderstanding that has been mentioned a few times already during the early days of the Silverlight 2 release.
General instructions: Don't panic!
Specifically: If you install the Silverlight Tools, which is the primary way to install the full package you need for Silverlight 2 development (namely: the developer runtime of the core DLLs, the SDK including the various client and server libraries, the VS add-in that includes the project templates), you might notice that it is versioned "RC1" and not specifically versioned as "RTM" in its install notifications, Help/About, Add/Remove Programs presence etc. The reason for this has to do with the intended servicing model for the add-in, so that the Silverlight tools themselves can be serviced per the current Tools team plan of record. Versioning the Tools as "RTM" would have dictated a particular servicing model that wouldn't have been as flexible.
In other words: that "RC1" really is the Tools kit you will need for Silverlight 2 (RTM version) development.
That is all ...