Yeah, I love how they're celebrating Portal for Mac and yet it tells me my Mac OS isn't good enough to run it.
Luckily I can still run it on my laptop.
The Mac port of Steam and the source engine (with no disrespect to Valve) could have been a lot better from what I've gathered. Part of it is Apple's fault as a lot of their graphics card drivers aren't up to standard but the source engine was optimised for use with DirectX rather than OpenGL, which is what just about everything (Windows, Mac, Linux, BSD, Solaris, some games consoles) uses so they had to move it to OpenGL for the Mac port...and the results could have been better.
They also haven't designed it well for running on Mac OS X anyway as it ignores a lot of design and functionality expectations from what I hear and it leaves a lot of things running in the background that really shouldn't, massively impacting gaming performance.
It's a shame but ironically running the windows version of steam using Crossover or Darwine may actually result in more speed on some games
