Here. "Web Services Enhancements 1.0 for Microsoft .NET (WSE) provides advanced Web services functionality for Microsoft Visual Studio .NET and Microsoft .NET Framework developers to support the latest Web services capabilities. Enterprise ready applications can be developed quickly with the support of security features such as digital signature and encryption, message routing capabilities, and the ability to include message attachments that are not serialized into XML. Functionality is based on the WS-Security, WS-Routing, WS-Attachments and DIME specifications."
In their own wonderful way, Microsoft has changed the name yet again to the set of classes that they've put together to do heavy-duty web services stuff. It was GXA, then WSDK and now it is, finally and officially, the Web Services Enhancements (WSE). If you liked it with the old names, you'll love it with the new name. : )