We've released two kits to help add information card support to websites. They both implement the Patterns for Supporting Information Cards at Web Sites: Personal Cards for Sign up and Signing In.

The Information Card Kit for HTML is platform-independent JavaScript and CSS code that detects if the client can use Information Cards and provides the corresponding UI support.

The Information Card Kit for ASP.NET 2.0 has additonal .NET code to process the token delivered to the server when a user selects a card.

For token processing on other platforms you can refer to the following open source projects:

Ruby on Rails Relying Party:
http://rubyforge.org/projects/informationcard/
http://www.codeplex.com/informationcardruby

Java Relying Party:
http://sourceforge.net/projects/informationcard/
http://www.codeplex.com/informationcardjava

Keep your eyes peeled for similar open source projects for C and PHP. In the case of PHP you can take a look at how Kim Cameron added information card support to his site.