Internet2 is a consortium being led by 207 universities working in partnership with industry and government to develop and deploy advanced network applications and technologies, accelerating the creation of tomorrow’s Internet. (that’s from their site πŸ™‚ )
Internet2 consortium made an announcement that Internet2 middleware software project Shibboleth will colaborate with Microsoft to enable support Windows 2003 R2 ADFS.
Quote from Shibboleth project description:

Shibboleth is standards-based, open source middleware software providing
both intra-domain and inter-domain single-sign on (SSO) capability.
Shibboleth implements the OASIS Security Assertion Markup Language (SAML)
standard specification, and is certified for use with the United States
E-Authentication Federation.

You can find full text of this announcement in the message posted on Internet2 community mailing list.