With my mac laptops I have consistently seen high battery life at the start and it has diminished considerably after a few months. Does this not happen with everyone else?
not here (sample size of one). I still get 5-6 hours use from my 1st gen unibody macbook; the one with the removable battery.
I have the 2nd gen unibody macbook pro ( the one without the removable battery ) and I still see 5 - 6 hours of battery life. I can usually get more if I'm just watching movies on it. Youtube & Hulu et. al. seem to be the biggest battery killers for me ( 4 - 5 hours )
I am impressed and dismayed by your experience. My 2 year old MBP (pre-unibody) gets only 45-60 minutes of battery time. Did the unibody MBP's see that much of a boost in battery performance?
Yes. Apple completely changed battery designs between the removable and the non-removable versions. The latter will last significantly longer.
Here's a video from Apple with a fantastic overview of the new tech:
I think they switched from a Lithium Ion battery to a Lithium Polymer battery. The latter performs much better and lasts a lot longer. Most new cell phones, and incidentally, RC Helicopters use this too.
based on your figures, hell yes. I know three people with the unibody 15" MBP, and all get 6+ hours life
A couple of years ago I had a Macbook Pro (not certain of the generation), and I don't think I ever got more than 3 hours of battery life out of it even when it was new. By the end of its life it was usually running for about 90 minutes before needing a recharge. Maybe I just got a crummy battery; dunno.