The ID card scheme, in far too much detail...

[denny]

I just looked this article up for a comment in someone else's journal, and it occurs to me that now is probably a good time to repost the link. Some of the information in it has gone out of date (generally in ways for the worse, e.g. compulsion), but in general it's a good guide to the whole mess:
http://www.theregister.co.uk/2004/05/05/complete_idcard_guide/