I believe that for now, it is more a matter of market share rather than technical problems that has kept many games from the mac. It might change.
Yes and no.
I'm a Mac owner (in fact, I own 2 Macs and one PC), and since the move to Intel CPUs, the Mac is at finally on a par with with a Windows box CPU-wise. That said, Macs generally don't ship with decent GPUs. The standard iMac (which, let's face it, isn't particularly cheap) ships with either an ancient Radeon X1600 Pro or a GeForce 7300GT, both of which frankly suck. Even the top-end 24" iMac only has an option
for a 7600GT, which isn't awful, but it's by no means designed for high-end gaming on the integrated 1920x1200 panel. As the owner of one of these machines, it's not an awful GPU, but it's not brilliant by any stretch of the imagination.
Even the scarily powerful dual-dual-core Mac Pro (which will set you back approximately a bazillion pounds) ships by default with at 7300GT. There's an option for a Radeon 1900XT, which is a nice card, but let's face it - it's not top-end.
Hardware is only part of the story though. Aspyr (one of the key companies that port Windows games to the Mac) have found that Mac OS X's OpenGL stack is significantly slower than Windows'. This seriously hurt performance of Doom 3-engined games, and there's nothing any of the third-party developers can't do about it.
Bottom line, as far as I can see, Apple simply don't see the Mac gaming as anything even approaching a priority. It's a pity really, because Mac OS X is a superb operating system, and they make lovely hardware.
Oh, and in answer to TorTorden's point about not supporting integrated graphics: Reading between the lines, they don't support the Intel GMA900/950, which rules out support for the Mac Mini, the iBook, and the MacBook. The PowerBook, MacBook Pro, iMac, and Mac Pro should be able to run Prey.This comment was edited on Jan 14, 11:18.