When will Mac Halo be released?

A: Unknown. As of this writing, the "unofficial" release date for PC Halo is September 21, 2003. Mac Halo will be released after that. SketchFactor from Bungie, in the PC Halo Faq, said:

The Mac version is in the capable hands of our friends at MacSoft and Westlake Interactive and is scheduled for a near simultaneous release with the PC version. All of the new features and extras that are being added for the PC will also be available when Halo makes its way to Macs later this year.