Today I sent a mail to OSIS-General on using OpenSSO for the Identity System/Selector that we are trying to build:

We at Sun would like to offer/suggest OpenSSO (
http://opensso.dev.java.net/) as a open source project within the OSIS
framework. I believe OSIS could benefit from the technologies that are
either already implemented within OpenSSO or 'very soon to be released',
including SAML 1.x, SAML 2.0, ID-* etc. For additional information on
OpenSSO, please take a look at Pat Paterson's blog at: 
http://blogs.sun.com/superpat/entry/recently_asked_questions_on_opensso
and 
http://blogs.sun.com/superpat/entry/first_multi_protocol_federated_ident
ity. 

Given the existing large code base of OpenSSO (and still growing), we should be a significant step ahead in the goal of creating a OSIS.