The Yahoo openid service is working now, although it is in “beta”. They only support openid 2.0 so it might not work everywhere. I tried several using sites that worked before using a different OpenID and yahoo gave me an error saying that they only support OpenID 2.0 because its more secure.

People were excited to hear the news earlier this month when Yahoo announced that they would support OpenID. The burden of responsibility now falls to the developers to implement the newest version of OpenID on their sites. Our dream of a unified login across the web might soon come true.