I've owned various Apple portables (as well as PCs) since the Powerbook 170. Until I owned a G4 iBook, Apple's battery longevity was nothing different than the PC counterparts. I bought a used G4 powerbook when that model was 1.5-2 years old. When I got it, the battery was good for about 6 hours of solid average use. I had it for five years (only replacing it with this Macbook I have now last year) and in all that time, the battery only ever lost about 30% of it's capacity. I still saw a solid 4 hours of use out of it per charge. It was by far the longest I've ever had a laptop battery last (even keeping the comparison to Li-Ions). Comparatively, this Macbook never got great life (maybe 3hrs tops) but in over a year, I've yet to notice it losing any capacity. And in the past, a year is about all the time it ever took for previous laptops' batteries to hold zero charge at all. I had a Sony Vaio that killed it's battery every nine months, and before I bought the iBook, I was just used to a $50 replacement cost annually or so.
From this article (as well as what I've heard from others) at some point between this Macbook and the current models, the batteries or charging method Apple's used have significantly shortened the usable lifespans. Which will probably prove annoying when it eventually comes time to replace this machine in another 3-5 years.