It's one of the higher-end MacBook Pros — 2G of memory, faster processor, etc. — so it's probably got a slightly larger appetite for power than normal.
I might also be giving you a bad measurement; it's very rare for me to run on battery. I just unplugged myself with a full battery while at medium brightness, and the predictor said 2:46; I lowered the brightness to the minimum and told it to optimize for "better battery performance", and the prediction changed to 3:06. I have no idea how accurate those predictions are, though — oh crap, they're probably low, because I just remembered that I'm running BitTorrent in the background, and it's probably performing a steady stream of disk traffic. Anyhow, I wouldn't put much faith in my two-hour figure.
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I might also be giving you a bad measurement; it's very rare for me to run on battery. I just unplugged myself with a full battery while at medium brightness, and the predictor said 2:46; I lowered the brightness to the minimum and told it to optimize for "better battery performance", and the prediction changed to 3:06. I have no idea how accurate those predictions are, though — oh crap, they're probably low, because I just remembered that I'm running BitTorrent in the background, and it's probably performing a steady stream of disk traffic. Anyhow, I wouldn't put much faith in my two-hour figure.