Solaris is pretty much developed from BSD (Berkeley distribution of Unix) uid0.
The difference between Solaris and the other flavours of Unix is mainly that Sun have been developing it inhouse for the last 15 years or so.
Now its not that the open source brigade are bad coders, quite the opposite, but the way open source communities work dosn't necessarily lead to a good commercial product. Also companies that buy operating systems need a support infrastructure which the open source distributions can't really provide.
If you're looking at seriously high security systems, usually huge multiprocessor Unix boxes, such as banking and financial systems then they wil generally be running HP, AIX or Solaris.
Should have me HD tomorrow so will install the beastie and report back.
