I've been using the Pearl with a Mac G5 for over a month now. There are a few small issues with the PocketMac Sync software, but nothing that can't be solved with a little perseverance and changing a default setting here and there. I think the new "intel" MACs have some incompatibility, but you'd have to search the forum about that.
I only need to sync my Address Book and iCal calendar, and it works 100 percent perfectly EVERY time! ***A powered USB hub seems to be the key to no problems. My SM Card mounts every time and I can drag music/video/pictures back and forth. I can also connect via Bluetooth AND use the Pearl as a Bluetooth modem!
There have been a lot of issues posted regarding the Pearl, but I have had NO trouble with mine - except the trackball-stops-ring issue, which is really NOT that big a problem - otherwise, it's WAY more stable, and syncs as well or better than the Palm Treo I had before.
About the ONLY thing I can think of that you CAN'T do with the Mac, is use the desktop software and install new OS updates. I'm using the original T-Mobile software that came with my Pearl (but connecting on the Cingular network), and I think the fact that I haven't "tinkered" with the OS is the key to my smooth sailing!