My two cents worth: From the time I first purchased my droid in mid December until now I have seen a major improvement in battery life. Some of the reasons for that are as follows: 1) it seems the battery performance improves after a few full charges 2) I used the droid when it was my "new toy" 3 times as much as I do now, having the high resolution display on for long periods of time will use battery 3) I have actually learned how to use the phone and that has helped. The phone has a built in battery usage meter that will point out where the battery is being used up..use this to identify and manage your battery use. Also, someone mentioned the power control widget earlier. I use this widget and would recommned it. Having the auto brightness turned on is a major help to battery life. Also, not leaving bluetooth on when not in use, and leaving wifi on when it's available will also help. I typically keep my phone off charge for around 16 hours and my battery drops to around 60% - 70%.
You are saying Auto Brightness on helps the battery? I keep mine on manual and at about 1/10th the brightness. I also have K-9 Mail which checks email every hour. Gmail is pushing and Seesmic checks twitter every hour.
I am a heavy user I'd say I get about 16 - 24 hours out of a charge. This is with texting light phone calling, light web browsing and listening to music about 2 hours total per day. I also run e-Buddy for about two hours a day.