Jeremy / Anonymous Coward:
It's physically impossible to manufacture a battery that will last an unlimited number of charge/discharge cycles, be it a laptop battery or rechargable battery for anything else.
Any battery will eventually loose some or all it's original capacity - so you can't blame Apple or any other electronics company for shipping timebombs.
I have a Toshiba Satellite Pro M30 laptop thats about 4 years old now and still working OK - screen not cracked, keys not broken, etc... Ive carefully looked after it.
When ever I'm going to use it for a long period without access to mains AC (e.g. watching a film on train journey), I charge it over night and also take a fully charged 12V 7.2Ah sealed Lead Acid with me, which I connect to the PSU DC jack. Since the PSU outputs 15V, I can get away with it for about 3 hours if I put the screen brightness on lowest and I don't use the optical drive.
Its a lot cheaper this way than buying a new Li-ion battery for the laptop.