Hi there, sabre364
Also, would the new hd4000 integrated graphics run it well?
Well, I have a mid 12 MBP 13'' 8GB running CIV V natively on Mountain Lion at native resolution. I read on the web that the HD 4000 would be a bit better than the one I had in my late desktop - don't remember the exact model now, I guess it was a NVidia 9600 . I don't know if it's because it's running on MAC OS X but the performance is indeed weaker than I expected... Settings won't get past medium - and with quite a bit of lag in the late game if you zoom out too much :\ Plus, the leader scenes are horrible... It looks like this HD 4000 doesn't have enough speed to build the leaders... they apper with spikes and black points...
On the bright side, the game runs quite smooth at low settings - even on the late game, so long as you don't zoom out too much. I'm currrently playing on a small map, modern era, with all tiles uncovered and I'm pretty much satisfied with the game's response times. Plus, it perfectly integrates with Mac OS - even in full screen I can check other programs - mail, safari, etc - then come back with only 0.5 sec delay. And if you don't like the leaders scenes, you can just cut them out to gain a little more performance.
All in all it's a very expensive low end gaming experience. Buy it only if you intent to do other stuff with it - like go to college for example. If you intent to play regularly on your Mac though, I'd suggest you study the possibility of buying a 15'' MBP - even 2010 versions should have better performance than the HD 4000.
Hope to have helped
P.S. I haven't tested playing via Bootcamp on Windows 7, but from what I read it should help to improve the game's performance.