I had the same issues everyone else is having. In fact the first day i used GB, the battery died in about 5 hours. All I had was a 30 minute conversation and normal usage beyond that. Very unhappy and frustrated since this problem continued on Thursday. I got all night starting at 10pm to about 430 before my phone went completely dead and I did NOTHING on it other than some texts and a 45 sec phone call. Not to mention, my phone was in night mode from 10PM to 5am. So I was not very happy.
However, Im happy to report that my battery life has improved today. The reason isnt because I just waited. Im sure that will help with the usage issue if this truely is a "smart OS" and can change and adjust power usage as it goes.
The reason is because I was fooling around with widgets and I accidentally clicked on the "power settings" Android Widget. You know the long box that has the 5 options for bluetooth, gps, wifi, night mode and media synch? Turns out that my media synch was tuned on!!! Now the reason I did notice this at first is because I use the motorola blur individual switches instead of the android ones and I didnt have a media synch blur switch set up.
I turned it off and now Im doing great. My meter looks to be about 50%, and Ive been on the battery for about 10 hours. So Im a happy camper now.
I remember reading in this thread or another forum(heaven forbid!!!!

) that someone kept seeing that his media synch was on and he was killing it with ATK, but it kept turning back on. Im no Android OS expert, but could this be because while ATK kills the task, if the switch is still on, it will just turn back on? Try the media synch switch in power settings. Ive now done away with the individual moto switches and use the full bar in its place. I get 5 switches for the room of 4 moto switches and I like the dark color better.
Anyway, I just wanted to pass this along to people who were having issues with battery life. Its something to check on and see if thats your problem. It has worked great for me. And I was ready to go back to VErizon and have them give me a new one, or restore Froyo. Neither of which I wanted because GB looks great and is super silky smooth. I couldnt be happier now. Well, if the battery life keeps improving, I will be.