Kudos to VJ for finding that Peter Tamte's new company Destineer will be publishing the Mac version of HALO:

Also prowling the halls of E3 was well-known Mac game publisher Peter Tamte, whose new company Destineer will be releasing MicrosoftТs Age of Empires II and Links 2002 for the Mac later this year under the brand Bold by Destineer. Along with other games from Microsoft and original cross-platform titles, TamteТs company will be publishing the Mac version of BungieТs epic, Halo.

IMG has the whole story.