My colleague Richard Turner has just done a Channel 9 CardSpace Simple Demo that begins with a detailed look at the user experience, exploring many features of the interface, explaining why we put them there, and showing CardSpace working with both IE 7 and FireFox.
It then moves on to a code walkthrough using visual studio, showing how to tweak your site so it accepts Information Cards (produced by CardSpace or other interoperable implementations).
I suspect the hardest part of enabling a site for Cardspace V1.0 is setting up the ssl certificate. And Richard must agree, because he has gone the extra length and produced a second Channel 9 video that shows How to Configure IIS to Support Windows CardSpace. I sure wish I had this when I started fooling around with this stuff!
The source code for the demo will be posted here this week. Richard is working on other related videos as well.