What could have been done better?
I spent a couple of years advocating for OpenID adoption, because I believed that the alternative (one or two companies controlling login for the entire Web, ala Microsoft Passport or Facebook Connect) would be a massive blow to the decentralised nature of the internet. I believed that OpenID's usability issues could be resolved if enough smart people got involved in figuring them out.
Clearly I was wrong on that last point.
And yes, my latest project (lanyrd.com) uses Twitter rather than OpenID for authentication. From a developer point of view, that gets me the benefits I hoped for with OpenID (SSO, portable identities, instant contact lists) without having to wait for the world to agree on the standards. I just wish we could have figured out a decentralised solution.