by Had a great presentation on illumos (www.illumos.org) from the project head last night at the Unix Users Association of Southern California, Los Angeles chapter meeting (www.uuasc.org).
Several top Solaris developers have created, from Oracles’s last CDDL release of OpenSolaris (and these releases have stopped, there’s no more OpenSolaris), an open-source fork of Solaris.
They’ve filled in the missing (proprietary) bits (like libc) by leveraging *BSD code (and their improvements on this code are now going back into *BSD). They do have a runnable system now, though no X yet. (You can install the commercial Solaris X package to get the functionality.)
Check out www.illumos.org for more details.