Looks like Garmin might be making good on their promise to have their GPSr's Mac compatible (by the end of 2006).
http://forums.macrumors.com/showthread.php?t=416287
I haven't tried it yet, but the beta is out there, hope it works. I've waited for 1 1/2 years for my 60CSx to be able to download PQ's. Kinda PO'ed at them for promising compatibility that long ago.