Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
How much time do you have a working battery?
I 3-7 hours
There are many factors that impact your battery life. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.

This should answer most, if not all, of your battery questions:
 
Typically I have Safari (3-6 tabs), iCal, Mail, iTunes, and Evernote open. Generally lasts 6-7 hours. If I am playing lots of videos from websites that time cuts off about an hour.
 
I get 3-5 hours with normal usage.

Lots of non-flash browser (though ads may be in Flash), 1 VM, lots of terminal
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.