Google has announced their intention to join the growing list of OpenID authentication providers. Except it turns out they're using their own version of OpenID that is incompatible with everyone else. It seems that Google will be using their own "improved" version of OpenID based upon research and user feedback of the OpenID system; which isn't backwards compatible with OpenID 1.0/2.0 in hopes of improving end-user experience at the cost of protocol compatibility and complexity.
As Google points out, this isn’t OpenID though. This is something that Google created that resembles OpenID masquerading as OpenID since that’s what people want to see – and that’s what Microsoft announced just the day before.