Note that the default WiFi setting is to turn off when the screen turns off. So if you didn't play with the phone much, WiFi was probably off most of the time.
You probably also get pretty good cell signal at your location, which alleviates battery usage.
During the three days of up time on a single charge, I did play with it another hour or two per day, downloading and trying out apps and messaging. I also used the bar code scanner for reading foods into my Calorie Counter (FatSecret) app.
I also use it with bluetooth in my car, either for calling or streaming via Pandora. I did that for maybe an hour or two total during the 3-day up time.
I have 3 bars at work and home. So working only as a cell phone, I probably could even get it to go to 4 or 5 days. But then, I only make 2-3 calls per day.
I mostly use my much more capable PCs for web stuff at home and work. I view my Droid more like one of those emergency donut tires in the car - nice in a pinch but I really want to get to a good PC ASAP, with a bigger screen and faster link and processing. I guess I'm just from the older generation.
I'm actually very pleased and impressed with the Droid battery time. I just don't understand all the complaints on this thread. Do you other guys ever get off your phone/SMS source/PDA/internet gateway thing? You must be constantly attached like those Borgs...
Just realized that would be, uh, ... Borgs on Droids...