AuroroaUX was the operating system that made a brief splash a few years ago for its unique design: an open-source OS that is based upon a modified OpenSolaris kernel while much of the rest of the operating system was to be written in ADA. The official mission of the project was "to create a highly reliable, mission critical, core operating system. AuroraUX uses the US Department of Defense-developed Ada programming language." Using ADA as a programming language for modern open-source software development isn't too common and unfortunately this OpenSolaris derivative no longer exists.
I hadn't heard anything out of the AuroraUX camp in likely more than one year. Today I see that the AuroraUX.org domain no longer exists nor the earlier auroraux.blastwave.org domain. The Ohloh tracking of AuroraUX shows the Git commit activity of the code-base from going around ~200 commits per month from 2006 through 2009, but since November of 2009 there hasn't been any commits. The tracking of the Git repository on AuroraUX ended in August 2011, likely when their domain went down.
In terms of other OpenSolaris-derived operating systems still in existence, there is Illumian with its 1.0 release from February of this year and this OS uses the Debian package manager, there is still SmartOS from Joyent, BeleniX is more or less dormant, Schillix saw its latest 0.8 release in August, MartUX as OpenIndiana for SPARC, and the latest OpenIndiana release is 151a5 from this past July. There will be new OpenSolaris-derived benchmarks likely out soon.