A lot of people seem to like the idea of a Debian GNU/OpenSolaris project. Alvaro Lopez started the discussion, and lots of people responded (mostly positive). Among them are Tim Bray (Sun) and Ian Murdock (founder of Debian).
The problem is (as you would have expected) the license of OpenSolaris (the CDDL). According to another blog post by Alvaro Lopez, people on the debian-legal mailinglist seem to consider the license non-free.
Now, if Sun would choose a proper license or dual-license OpenSolaris (CDDL + GPL or something), things would look mighty different, I guess...
(via Ian Murdock)