XAuth is a standard that is going to help make the social web smarter and more relevant. The goal of XAuth is to create a more relevant social experience across the web, and it is truly exciting that all of our partners are united on this front.
Intelligent Social Tools
XAuth enables developers to check if a user is authenticated with a specific set of services with at most a single HTTP request, and can help reduce the number of requests needed when a site uses multiple social services
Evolution of the Standard
XAuth is only available as a preview right now for service providers and developers. Meebo, Google and Microsoft have put together a few demo pages to give developers a preview of what will be possible.
You can got to xauth.org/info to learn more about XAuth. In the future they will continue to move forward on XAuth and collaborate further with additional partners, the Open Identity Exchange (OIX) and the OpenID Foundation to facilitate an open consortium to host the XAuth technology.