OpenID Provider - Specific user roles can be given the capability of using the built-in OpenID provider, turning their author posts URL into a valid OpenID which can be used to login to other sites. This includes support for OpenID 1.0 and 2.0 as well as Simple Registration 1.0, with hooks to add other OpenID extensions.
OpenID Delegation - Users authorized to use the built-in provider can optionally choose to delegate their OpenID to another provider instead.
EAUT Mapper - Support for the draft Email Address to URL Transformation protocol. If you use an email address at the domain of your WordPress blog, you can now use use that email address to login wherever EAUT is supported.
Extensibility - the plugin now has a number of public functions and hooks that other plugins can use to integrate with or extend the OpenID plugin. These are all documented here.
It’s worth mentioning that pretty much all of the new features require that you also have the XRDS-Simple plugin installed. There are also a number of other changes in regards to simplifying and stabilizing the plugin, than can be read about here.