To all those that have asked me for an advance copy of the CardSpace Authentication Provider for DotNetNuke I thank you for your patience.
The provider is now a part of the standard DotNetNuke installation in DNN 4.6. Right now you'll need to sign up to the DotNetNuke Beta testing progam here: http://www.dotnetnuke.com/LinkClick.aspx?link=1123&tabid=510&mid=2027
Please send any feedback to me. The installation instructions haven't been published yet so unless you've got some CardSpace deployment experience you'll probably have an issue or two. Firstly, remember that you'll need SSL on your web site (shared SSL will be enough) before you can even contemplate using CardSpace on your site.