Emagic has released Logic Platinum for OS X:
Emagic GmbH is proud to announce the release of the very first version of Logic Platinum 5 for Mac OS X. This is accompanied by the simultaneous release of Mac OS X hardware drivers for Emagic's range of USB MIDI and audio interfaces.
This pages discusses some of the differences in the OS X version.
Apple acquired Emagic in July. Windows-based Emagic products are scheduled to be discontinued on Sept 30.