I managed to get Oldblivion working on my fiances macbook (2.0 C2D White) It actually worked really well. You lose some of the "pretty" factor, but you can get around 20-25 fps and get the awesome story line. Something I found interesting is that she was able to play Oblivion on battery for about 2.5 hours, before the battery died. For oldblivion go here:
http://www.oldblivion.com/
I remember having to make a setting different so that it would start...if I remember, I'll edit. This should work slightly better with the newer revision macbooks. Not a ton, but enough
Good luck.
Also, my 2 cents about not putting dedicated graphics in the macbook. Battery Life! You'd lose quite a bit, even if they decided to put an 8400m gs in there. I admire apple for keeping with the integrated. As technology progresses, I'm sure we'll see some form of a dedicated graphics, but for now, be happy that you can get nearly 5 hours out of a very powerful laptop, even if it does have integrated graphics. Try playing a game on macbook pro, suddenly you only have 1 hour of battery life. They each have their ups and downs.
Trent out