My i7 MBP has been on for about 2 hours since I got home, and its at 44* C right now. It runs cooler compared to my 2008 MacBook, which was in the high 40s/low 50s most of the time.
Of course, when the nVidia chip kicks in, it's a totally different story. 😀
As for the new MacBook, my gf just bought one the other week and hers runs very cool. However, she doesn't do anything remotely intensive, the most she really does is a powerpoint presentation lol.