There are some serious advantages to being self employed and picking up the tent at a moment's notice and moving to a new campsite is one of them.
The flight to California is a little over 5 hours from my local airport and while I have had excellent battery life from my MacBook so far, I decided at the last minute to run over to the Apple store and grab a spare. It took a few hours to charge but it was ready prior to leaving at oh-dark-thirty on Saturday morning.
Since I left so early I actually snoozed for the first 2 hours of the flight. I then decided that I really needed to get some of my work done and fired up the MacBook, jumping between a couple of different tasks. I had read that someone got significantly better battery life by turning the brightness of the screen down as low as they could, so I tried that.
Turns out I probably didn't need the spare battery because by the time I was told to put the MacBook away for landing I still had 48% left on my battery. Most of my work had been in text editors and iStat Menus always showed very low CPU utilization and disk activity so that contributed greatly. Adding to that the fact that I had the AirPort service turned off the MacBook just didn't burn up that much energy.
If you have a MacBook you may have noticed that there is a little button on the bottom of the battery that, when pressed, lights up to indicate the charge left in the battery. What I learned was that this also works when the battery is out of the machine. Nice feature.
I have read many stories about the poor quality of the batteries for the MacBook, quite a few directly from the feedback listed in the Apple Store. Most of them appear to be for the last generation of the MacBook so I hope I'm not just lucky with my MacBook's battery life and that perhaps Apple has resolved what appeared to be a serious problem. So far I have had excellent performance from mine.
For the last 3 days I have been running almost exclusively off battery power and the amount of time I get from the battery has been outstanding. Much better than what I have gotten on the Dells or HPs that I have owned.