That isn't the point.  How many forums do you visit?  How many vendor, bank, or government sites?  How many of those sites impose different security requirements (password length, no duplicate usernames) which invariably force you into remembering multiple accounts and passwords.  How annoying is it to have to fill in the same forum registration form when all that information could be automatically provided.  Since most of us auto-login via cookies, how cool would it be if you could just click on a visual representation of your account and let the authentication mechanism do the rest?

I'm new to Cardspace but the general idea has been around for a while.  Being able to associate a card with multiple sites is incredible improvement and has the potential to greatly enhance and enrich the end-user experience.  Think of the potential possibilities; perhaps where you change your card info and your profile is updated across all sites that card is associated with?