I'm not sure if you guys know, but the 60/30 fps change is based on VSync and the way the frame buffer works, VSync is a necessary evil on LCD's to keep from experiencing 'tearing' by having unsynced fps #'s, when you're getting 60FPS, you're actually getting equal or greater than 60 fps but it caches/buffers it and only spits out 60 of those frames, when you get 30, it means you're above 30 but below 60 and it caches/buffers it and only spits out 30 of those frames, things look best at numbers easily divisible into 60, so 20, 30, 60 are generally 'playable' frame rates, where 60 all the time would be preferred but anything over 30 is where the speed should be in order to keep the game working smoothly. The number 60 coincides with the refresh rate of the LCDs in our Macs, some LCDs are capable of 75hz or 120hz, but not the ones in our machines, and not in most machines actually either, 60 is the defacto standard for LCD refresh rate with 120 and higher catching on in the TV/3D line ups in order to provide motion blur or dual pictures at the same frame rate as one another, so yeah.
If you're interested in a bit more reading:
http://en.wikipedia.org/wiki/Vertical_synchronization
http://en.wikipedia.org/wiki/Screen_tearing
http://en.wikipedia.org/wiki/Refresh_rate
You guys will probably all get 30 or 60 fps all the time with small fluctuations up or down 1fps just because of a rounding fluke in the way the application reports fps.
So if you really want to test what the machine is capable of, disable VSync and see what the frame rates are, but be aware you'll see a lot of screen tearing on an LCD with non divisible into 60 frame rates that are not 20/30/60, it's just the way it is. You're better off leaving VSync enabled and enjoying a smoother gameplay experience and "losing" a few fps than you are disabling it and dealing with all the tearing.
I hope that 10.6.4 brings some graphics performance improvements, it seems a lot of the focus is going to graphics drivers so I hope that is the case.
Also, HL2 is based on the same engine as CS:S, and since HL2 was updated to the new engine already and released 5/26, I can only expect that CS:S is closer to release than some of you may think.