I disagree- I am able to reach 5 hours when I am especially cognizant of power savings. For example, when running spreadsheets and some stats software, I can extend life by turning Wifi off and keeping screen brightness down. This includes running data visualization programming, which is a bit more CPU intensive.
BTW: I have been doing *very* unscientific test with my friends' MBP (new models). The results have the MB coming out ahead for battery life in every test. On average, I my results point to about a .5 hour benefit in battery life for the MB. To be fair, these guys are CS professors and, even though they report leaving wireless off, I am skeptical (they show symptoms of withdrawl when they are not reading Slashdot!).