I while ago I wrote that there is an experimental version of the Live ID login page that makes use of Information Cards linked to your Live ID account. Unfortunately this login form was only used for very specific services (hotmail only at that time IIRC).

I am happy to see that more and more sites these days use the InfoCard enabled sign in page – and more importantly – sites I actually use (e.g. MSDN, Live Mesh, Connect…). Way to go!