This PDF is a good place to start:

OSX Cheat Sheet
[EDIT] As of 1/16/08, there are some typos in the OS/Avid version section of the pdf. anything marked "X.8.x" should be "x.4.x" In addition, Here are the current requirements for running Avid on an Intel based Mac. Desktops: Mac Pro 2.66GHz or 3.0GHz Dual-Core Intel Xeon. With: NVIDIA GeForce7300 GT w/256MB SDRAM iMac 24” 2.33GHz Intel Core 2 Duo processor With: NVIDIA GeForce7300 GT 256MB 20” 2.16GHz Intel Core 2 Duo processor With: ATI Radeon X1600/256MB VRAM or 128MB VRAM 17” 2.0GHz Intel Core 2 Duo processor With: ATI Radeon X1600/128MB VRAM Laptops: ** MacBook Pro 17” 2.33GHz or 2.16GHz Intel Core 2 Duo 15” 2.33GHz or 2.16GHz Intel Core 2 Duo ** PLEASE NOTE: - 7200 RPM Internal Hard drive recommend for internal storage, though not required. - MacBook laptops are not supported for this Program. - Mac Mini desktops are not supported for this Program. - 17” iMac 1.83GHz w/ Intel GMA 950 graphics will not work properly. New Ram Requirements: - 2 Gig of RAM is the Minimum for Desktop & Laptop users. - 3 Gig of RAM Recommended (for HD or high stream count projects) - 4 gig of RAM is also being tested on MacPro systems.

A good list of supported devices for M.C. 3.0 can now be found here.