I don't think enough people appreciate just how awesome of an OS Solaris was. I never had opportunity to deploy it full-scale for any projects, but I lamented the loss of great potential when it "died."
It didn't die. It was forked by the community when Oracle close-sourced it. The community fork (called illumos) is being actively developed by multiple companies, which have done significant new feature work (e.g., http://dtrace.org/blogs/wdp/2011/03/our-zfs-io-throttle/).
The first and only time I used Solaris, I tried to run our application and got the error "System out of colors" or some such. Swore then and there never to use it again if I could help it.