http://blogs.msdn.com/cesardelatorre/archive/2007/05/24/how-to-use-cardspace-to-secure-web-applications.aspxUsing CardSpace to secure a Web Application..., that sounds interesting... We can also use CardSpace for securing WCF-Services for SOA application, but I leave that for another posting. :-). For a Web Application, we need to implement CardSpace withinen-USCommunityServer 2.1 SP1 (Build: 61025.2)