I posted about my difficulties connecting my Samsung Moment to my Mac laptop. If you want to, you can read those trials and tribulations.
If you just want the solution...
After looking for drivers, doing various experiments, and getting feedback from others with the same problem, I just hunted for any and all settings having to do with USB and one finally worked. It may not be perfect, but this seems to help.
Go into Settings -> Applications -> Development on your phone's main menu.
Turn on USB debugging ("Debug mode when USB is connected"). It will recognize that a USB connection now exists.
A widget will pop up on your Mac saying it's recognized a network device and will want to install the phone as a modem. Don't worry about it. It's a red herring. I never configured that, never connected that.
Go into "Notifications" from the phone's main menu and you'll see a notification under "Ongoing" that says "USB Connected (select to copy files to/from your computer)". Touch it.
You'll get a dialogue with the title "USB Connected" and the text "You have connected your phone to your computer via USB. Select 'Mount' if you want to copy files between your computer and your phone's SD card." It offers options of "Mount" and "Don't Mount". Touch "Mount".
A removeable drive will appear in Finder called "No Name". That's your Micro SD card and you can begin copying files. You'll need to unmount the card for applications on the phone to have access to it. I created a folder called "Music" in the DCIM folder, put a couple of MP3s in there and I'm listening to them now.
Don't know if this will work with Snow Leopard's built-in sync program or third party sync programs, but I'm happily able to move media back and forth which is HUGE for me.
UPDATE WITH SOME IMAGES
This is what the "main menu" looks like. When you're on the home screen and press your menu button/key, you'll get these options... Add, Wallpaper, Search, Notifications, Settings.