The solaris source code was open, i believe in 2005.. then came OpenSolaris in 2008.. and then the Illumos fork, if i recall correctly in 2010, after Oracle bought Sun..

But even in 2005, when they decided to open the source, it was already too late, because Linux was already a big hit by that time.

But, to use Illumos as a first machine, can be really painful, exactly because of the lack of adoption, and the lack of drivers and software as a consequence... that's the reason of my comment about the time to open the code.. and Oracle closing it up again, didnt help it either.

I would definetly consider Ilummos as a server node.. but for a personal machine.. it can get painful really easy, if you use for development like i do.