The number open source Unix flavors seems to be multiplying of late. At
a minimum, there is
Linux (okay, maybe you don't consider it Unix)
NetBSD
FreeBSD
OpenBSD
OpenDarwin (the basis of OS X)
OpenSolaris (this is new, and perhaps the only System V variant left!)
There may be others, but these are the ones of which I am aware.
I expect that the trend is going to be for vendors to target Linux even more as time continues. I remember how overjoyed *I* was when I tossed SCO 3.2.4.2 for RedHat all those years ago.
