illumos was already being used in production in 2010. Its development model is very much as the linked article implies -- every commit is expected to be stable,

illumos was already being used in production in 2010. Its development model is very much as the linked article implies -- every commit is expected to be stable, since the tree should always be stable. If you're looking for a general server OS, use OmniOS. If you're running armies of VMs, use SmartOS. For desktop, OpenIndiana Hipster, although illumos is more for servers. Personally, I'm fond of SmartOS, in large part because it comes with pkgsrc. The bad old Solaris days, with its anemic packages, blastwave and sunfreeware, are long gone.