Simon Willison’s Weblog

Stack Overflow Blog: OpenID, One Year Later. Google’s support is a huge deal—61% of Stack Overflow accounts use Google. Google’s implementation of directed identity has caused problems though, since Google provide a different OpenID for each domain making it hard for Stack Overflow, Server Fault and Super User to correlate accounts. Their solution is to require a (verified) e-mail address from Google OpenID users using sreg and use that as a key for the accounts.