You don't want to be sullying your Mac with (in this case) unnecessary windoze applications. The Mapsource equivalent program, "Bobcat" has now been released and re named "Roadtrip". As far as I can see, it does everything that Mapsource does on a PC, and the user interface is nicer. All the other supporting bits of software such as the webupdater and POI loader all have versions that run natively on a Mac now, and I believe that the latest versions of all of the mapping products will now load directly on a Mac as well as a PC.
Go point your browser
here to download the Mac applications from the Garmin site
Cheers,
Paul