I have the same problem on my Mac Pro. I upgraded 2 machines, a 2007 MacBook Pro 2.33 GHz, and an early 2008 Mac Pro octo 2.8 GHz with Apple 30 inch Cinema Display. I use the Eye1 Display2 hardware calibrator, and have been calibrating to Gamma 2.2 for years as recommended in the Adobe Photoshop Mac Forum. The MacBook Pro has no issues with display profiles, and looks the same as before. The Mac Pro, however, was a different story. As soon as I upgraded, the display just looked wrong to me. The screen lacked contrast and looked quite soft, almost blurry. I immediately booted back into a clone of my old Leopard installation to check, and sure enough, there was that punchy contrast & solid color I'd grown accustomed to. The comparison was run using the same profile on the same hardware. Only difference was Snow Leopard.
I am pretty sure that Apple did not change the GUI in Snow Leopard, especially because my MacBook Pro looks exactly the same as before. I think it is an OS bug with certain displays. Also, the fix you mention has no effect on my Mac Pro. Not only that, but I can't create a satisfactory display profile for that display in Snow Leopard, and the very same profile that worked great before the upgrade looks washed out in Snow Leopard.