Oracle completed their acquisition of Sun Microsystems in February 2010 and shortly thereafter removed OpenSSO downloads from their website in an unannounced policy change. OpenSSO will continue to be developed and supported by ForgeRock under the name of "OpenAM."http://en.wikipedia.org/wiki/OpenSSO#cite_note-0
OpenAM is project which took over the OpenSSO. Further info at http://www.forgerock.com/openam.html.