The stats in that link concur with what I wrote. Approximately 7 hours doing work online and over 4 hours playing movies (the 2 movie figure I mentioned). Maybe it's my anti-glare screen giving me better battery life. I mean, producing the glare on those other screens must use up some juice.
I suppose that the batteries in the new 13 and 15" machines are of a lesser capacity so may not run as long given the same usage.
Apple is legendary for over-optimizing for the typical use case (see also glossy screens, the on-again off-again love affair with Firewire, ExpressCard, etc.)
I completely agree (with you, not Apple).