GameSpy is running a four part article on Mac gaming and porting (one, two, three and four to come), starting with the roots of the Mac community in earlier Apple hardware, like the Apple IIe and vintage games like Wizardry (ah, the memories) through ports of Windows games like Doom, Mac originals like Myst, and up to the current process of porting games from OS 7/8/9.x to the very different underpinnings of OS X.
Halo gets a mention, even though it isn't yet out for the Mac:
Speaking of Halo, during that excruciating wait for DOOM, a small company in Chicago had plans of their own, plans that would include World Domination. But more on that later.
The later in this case comes in History Lesson Six of part 2, which is devoted to Bungie and mentions Pathways Into Darkness as well as the Marathon and Myth franchises.
Part 3 will focus on shareware, and Part 4 on porting houses. Halo may get another mention there if they mention Westlake Interactive, which they surely will.