WSE 2.0 SP2 released today!  Customer fixes included, plus a new security token (KerberosToken2), which supports impersonation, delegation and authentication in Web farm solutions.

Download from the MSDN Web Services portal:  http://www.microsoft.com/downloads/details.aspx?FamilyId=FC5F06C5-821F-41D3-A4FE-6C7B56423841&displaylang=en