Technically. If you consider The Open Group as some sort of authority. But Apple's OSX shows how meaningless it is to recieve the expensive POSIX "certification" from The Open Group. Alas, there is nothing in the spec about having to actually perform. Nothing that requires clean design or reliability, let alone transparency. I mean, if you want to use UNIX for a commercial product, by all means go ahead, but the least you could do is not ruin it.
"Certified UNIX". Pure marketing. Apple has the budget. There are vastly better UNIX implementations (from which Apple has borrowed copiously) that will never be certified. Go figure.
From where I sit, the most talented coders always seem to hold the POSIX specifications in spite. They do not like them. OSX is proof that they are not being unreasonable by taking that view.
To be clear, I'm not endorsing GNU/Linux. That is a whole 'nother story of UNIX gone bad.
