Top of the line MBPro(s) have discreet graphic cards so they're fine.
I for one will have to wait for a refresh to get to play this game (the first one was amazing at the time)
Mine has a discreet card but I'll never use it since it requires me to pretty much reboot the machine to switch it on (which now takes ages on Lion), and you then have to switch it back off when you're done playing
It also makes the machine sound like a jet engine and overheats within an hour. And it barely makes a difference in performance, some things actually run slower on it (like Photoshop). A pointless feature that I regret paying loads of money for!
Integrated graphics should be supported, even if it requires you to switch down the game resolution and turn off fancy graphics like water reflections or whatever. It's something other games have been doing for ages, such as the Half-Life series, which runs decently on a 10 year old PC with a 4MB graphics card if you turn all the settings to minimum.
It's just that most companies are lazy and just port their games with automatic software, and then their game eats 10 times more resources than it should
But they don't care, since they have contracts with PC manufacturers who pay them to bring out games with higher hardware requirements anyway.
The sad thing is no matter how awesome a machine you buy today, in 2 years it will not be able to run anything new decently, and it's not because software is evolving so fast, it's because companies don't care about optimising their code, it's not in their interest!
.........from most macs owned! 
