Not true. New macbooks and 13" macbook pros meet the minimum requirements and they have integrated chips.
Just thought I'd add my own experience here. I have the white macbook from late 2007. Almost identical to the OP's except my model has the GMA X3100 graphics chip instead of the 950. However, it is still an integrated chip.
I bought SC2 last night and installed it on my computer, both in OSX and windows 7 through boot camp. Only hiccup was a message saying my video driver "may not be compatible" while installing on OSX. However, the game runs at playable FPS in both OS's. On the lowest settings of course.
Now, there are issues and there is good reason Blizzard didn't include these chipsets in their minimum requirements. It gets a little weird during in game cut scenes and the mouse lags slightly. Also, under windows going to the in game menu to adjust video settings crashes the game. However, this doesn't happen to me under OSX.
All that being said, I still find the game playable. During game play it really is fine, except for the minor mouse lag mentioned, but I can deal.