So, how does CardSpace add value to a site like, say, OhmBlog ? There are a few potential applications: Authenticating as an admin with an InfoCard. This is a nice convenience because I don't have to remember my admin userid and password. Allowing users to register and login with their InfoCards. Kim Cameron led the way here with his IdentityBlog . Kim only allows authenticated users to leave comments on his blog. Requiring users to submit an InfoCard in order to leave a comment - this is to prevent spambots from drowning your blog with their drivel. DasBlog's "Captcha" feature also works well here, but CardSpace is harder yet to script, because it puts up a private secure desktop. Picking up personal information from the claims in the InfoCard and using them to populate the commenter's personal information (name, e-mail address) when leaving a comment. I've implemented support for the first 3, and will add support for the fourth shortly (after the work that's already been done, it should be trivial). Next, I'll talk about how a developer would add CardSpace support to a website... Read More...