Liberty Alliance
The Liberty Alliance, also known as Project Liberty or the Liberty Alliance Project, is a consortium made up of more than 150 companies and organizations that wants to create open standards for Identity Federation, Single Sign-On and related technologies. It has been founded in 2001 by Sun and several partners to build a decentralized and open alternative to the centralized and proprietary Passport system by Microsoft.
The Liberty Alliance framework heavily focuses on webservices as well as web applications with user interaction through common web browsers. It uses SAML to convey authentication and related information.
One free implementation of the Liberty Alliance standards is LASSO: A C library that supports the processes that are needed for the most common Liberty Alliance profiles and also is usable from other programming languages through the use of SWIG. Closely related to LASSO is SOUK, a Python framework that uses LASSO and actually implements the Liberty Alliance profiles.