As we finally have time to perform the upgrade work to make the Silverlight Streaming service work with the Silverlight 2 RTW bits, it is important to note that your applications hosted in Silverlight Streaming will also have to be updated to use the Silverlight 2 RTW bits.
There is good information on ScottGu's Blog describing how to upgrade your applications from Silverlight 2 Beta 2 to Silverlight 2 RTW smoothly, so they do not break when Silverlight Streaming is updated. Note that this should not impact your Silverlight 1 applications hosted in Silverlight Streaming.
This service maintenance work is scheduled in the next few days, I will be posting updates on this blog to keep you informed.