Apple - How long should my MacBook Pro battery last?
It's likely that you are running something in the background (such as Skype) which is triggering your dedicated graphics card, despite it not actually doing anything graphically intensive. This is a known issue in Apple's graphics card switching technology.
Download and run gfxCardStatus and see if I'm right. If so, close the problematic program or use gfxCardStatus to manually switch to the much lower-powered integrated chip. You should get longer battery life after that; I haven't directly measured it but I know I get at least 30 minutes to an hour of extra life.
And of course it also depends on what you're doing with your computer, what background programs are running, the brightness of your screen, etc.
Run Activity Monitor and watch the graphs and stats for a while when you are using your machine. Is there a bunch of threads that seem to be 'busy' even though you're not particularly doing anything? Yes? Have a look at the processes that own these threads and see if you're actually using those apps or if they're just wasting your battery.
Here's an Apple Support article that walks you through the whole thing, with screenshots too.
I did this and found the two worst culprits were:
backupd. This is Time Machine running. Let it run - it is important and eventually stops.
'Flash Player (Safari Internet Plugin)'. Even though I wasn't playing any Flash Video, it seems that some Flash files just burn through CPU because they don't have a proper 'idle' state. My solution to this was to install 'ClickToFlash' plugin for Safari which allows you to control which sites run Flash automatically and which do it on your say-so.
Just doing (2) doubled my battery life on my MacBook Pro 2,2 as a large proportion of my Mac-time is reading news and articles on the net. Many pages use Flash for advertisements and videos, which we know, but you may not know that many sites use Flash just for the nice fonts that they embed into the file (sIFR text).
I have the MacBook Pro 6,1 (i7, 4GB, 250GB 7200 RPM Drive).
I get around 6-7 hours when using it for browsing and email. Normal standard stuff. When running Parallels or playing Games I get around 4 hours. Overall I am extremely impressed with the new one's battery life. Watching videos I can push 4 hours out as well, which I do quite often.
My old MacBook (Dual Core, 4GB, 5400RPM Drive) still gives me around 3-4 hours battery life after 3 years.