Yes, the Forerunners are Mac compatible. I have a 301. I'm looking to upgrade to a 305 but I want to try it on to see if it fits on my wrist.
Garmin Training Center for Mac is not identical to GTC for Windows. I actually use both - GTC will run fine under Parallels so I assume that it will also run under VMWare Fusion or Boot Camp. But there's always MotionBased online.
They've recently come out with a 405 (more watch-like, without multi-sport capability, smaller display, but said to fit better on small wrists) and a 50 (foot pod only, no GPS). I'm not aware of any new planned fitness products right now. They've been having so much trouble with the Edge series I think it's time they stopped coming out with new hardware and put some more effort into their firmware.