OS X is Unix
@Chris iverson : nope, OSX is fully certified UNIX, as of 10.5:
http://www.apple.com/macosx/technology/unix.html
@Charlie stross: with Apple developing technologies like Open CL & Grand Central, 10.6 introducing full ZFS support, FSEvent enabling powerful features like Time Machine - I think you're mistaken in not seeing the innovation that's taking place in OS X.
The omission of OS X from this article is pretty glaring. Millions of people will be unwrapping christmas presents this year that are OS X powered (iPod Touches, as well as iPhones and Macs). OS X might not be a big hitter in the enterprise space - yet - but that's the enterprises' loss really.