UPDATE: Thanks to Rick for pointing out that when you follow the link, you'll see a button allowing you to download Microsoft Pre-Release Software WinFX Runtime Components – Beta2. Click on that button. InfoCard is part of that Beta. Sorry I didn't make this clearer.
This is still not the final UI – which is continuing to evolve. There are also some known “issues”. One is that when you export your cards and reimport them, the keys change. Another is that there is an incompatibility with tablet PC meaning that, on tablet, you can only use InfoCard once and then need to reboot.
None the less, you will get self-asserted cards out of the box (though there is no box). I'll also be posting links to some managed cards so you can try that out.
For those who are interested in building relying parties and identity providers on the Windows platform, you'll get everything you need here.
Once you've got an infocard, go to “Login” or “Dashboard” at the top right of identityblog and leave a comment… Let me know wht you think. There's no moderation – with an InfoCard you can publish directly to the blog.