The Open Group certifies Mac OS 10.5 (Leopard) is compliant with their UNIX 03 standard [opengroup.org].

In the past some folks have said, "OS X is not Unix." Hopefully this certification will be the end of that.

The certification:
[opengroup.org ]

News article:
[macworld.com ]

If you're trying to convince IT you need a Mac on your desk or in your server room, this news might help.