Windows CardSpace

I'm trying to get a handle on what exactly it is, I googled it but the explanation ran to several pages.
Can anyone dumb it down for me ?

What is is it, why would you use it and does anyone here use it, what are the advantages?

No. I don't use it, nor would I use it.

It is for managing "cards" which can be used for logging into compatible websites (primarily ones using LiveID). Or you can send them to other CardSpace users, if you want to give someone an electronic business card, for instance.