I have the new 13 macbook pro (with new battery) and I get 6 hrs out of mine if i surf the net and then watch a movie (video 2:30 hrs and internet around 3 hrs)
Thats with brightness on the 3rd notch and my backlit keyboard off
But if I rip a DVD using handbrake I only get 1 1/2 hrs!!!! with the brightness on 6th notch and the keyboard off.