macbook pro absurdly small battery life
Make sure there are no processes hogging your CPU (this eats battery).

Open Activity Monitor from /Applications/Utilities.
Set the Show menu at the top right to All Processes
Click the %CPU column head so the triangle faces down.
Which processes are at the top? How much are they using?

This may reveal what's going on.

Also, you can check the health of your battery to make sure it's not a hardware problem.
Download the free coconutBattery app and see what it has to say about your batter's capacity.