New MacBook Pro batteries have higher capacity?

I'm pretty sure its a bit of both. IDK about direct fitment into an older computer.

If I can recall correctly, the 15" and 17" have 30% more energy-efficient dedicated GPUs and automatic GPU switching. The 13" has a bigger battery, from 58 watt hours to 63.5.

These are compared to the mid 2009 models.

Wirelessly posted (iPod Touch 2G 8GB: Opera/9.80 (iPhone; Opera Mini/5.0.0176/764; U; en) Presto/2.4.15)

Im not sure, but I think that the 8-9 hours comes from the automatic video card switching and other "improvements" such as the apparently less bright screen.

EDIT: Oops, someone beat me to it!