[mgedmin]

OpenID doesn't replace user accounts. It replaces account passwords. A site, instead of verifying a user's password, contacts the user's OpenID provider asking them to verify the user's identity.

Instead of using the same username + password combination for all the sites on the Internet (and suffering from Gawker-like incidents), or writing down a bazillion passwords in my keyring, I use my OpenID when I want to comment on random people's blogs or sites like StackOverflow.