According to a recent edit at the OSIS wiki, the Higgins project has repositioned itself slightly and sharpened its focus on what they call an Identity Agent:

Higgins is an open source project hosted at the Eclipse Foundation. Although Higgins components can also be used to create IdPs and RPs, the focus is on creating a framework for “Identity Agents (IdAs)”. An IdA is a local or hosted service that manages a users multiple identities. It sits between the user’s remote IdPs (e.g. employer, bank, etc.) on the one hand and various RPs (e.g. websites, enterprise apps) on the other. The Higgins IdA is invoked by the user’s browser, manages the user’s identity information stored remotely at the user’s various IdPs using a variety of protocols, and supports a “card selector” user interface for release of identity information to an RP. The Higgins IdA is both protocol- and platform-independent, and is written in Javascript and Java. When used with CardSpace protocol RPs and IdPs will be able to act as the equivalent of Microsoft CardSpace “identity selector”. Support for OpenID, Liberty, Shibboleth and other protocols is also planned. Higgins defines a data model that allows identity information to be integrated from a wide variety of sources using plug-ins to the Higgins framework.

I’d add that due to Higgins multi-protocol and multi-platform nature, it is a full superset of Microsoft’s CardSpace implementation in Windows Vista.