The Hands On Lab materials for WSE have been updated for the WSE 2.0 SP2 release and now include VB.NET code as well as C#. If you're looking to get started with WSE 2.0, these provide some great grounding material.
Service Pack 2 is final and available on MSDN.
There was one additional fix between the Pre-Release and the final build involving policy processing for clients that do not send the WS-Addressing headers. In this case, request policy was being applied correctly but response policy would not be applied.
Please report any issues you find on the product to wsefeed.