Upon reading a few more posts, it's becoming obvious to me that one of two things has happened:
The first possibility is that a lot of you have defective phones that are drawing a hell of a lot more current from the batteries than they should. In this case, the battery will be quite warm to the touch even without using it (leave it setting on the desk for 15 mintues with the screen locked and dark before feeling it). I find this to be feasible: If it happened to one, it probably happened to an entire lot, seeing as they all came from the same factory using the same assembly lines using the same parts.
The other possibility is that some of you must be using every damned radio that phone's got for the entire day while downloading youtube after youtube on a 3G network... I mean, I don't even have 3G. I turn my wifi and GPS off at work (can't connect to the work network anyway -- against SOP) and I still have over 60% of my phone's battery left after I get home (I want to think I had 74% the other day, and that was with only about an hour of talk time the entire day and almost no other usage). Admittedly, even this is a good deal LOWER than the projected standby time of ... what was it, like 300 hours?
I use the phone as a BACKUP to other more powerful devices. It's an excellent SPARE. Sometimes I'll even use it for my e-mail or posting here simply because I get lazy after work sometimes. But you CAN'T use it IN PLACE OF a full-fledged computer system and expect it to last all day. They didn't market it for teenagers who have to talk to their "BFFLs" all day long inbetween and during classes and after school and when you're 10 feet away from each other in your respective cliques during cheerleader practice or band camp. At least, judging by the only TV commercial I've seen for it, they appear to be marketing it to those individuals who lead busy lives away from home and occasionally need some bit of info or contact through the Internet.
Seriously, get a car charger or something. If you're not a teenager, you probably drive anywhere from 15 to 30 minutes between work and home, and that's more than half a charge on the phone (at least in my case). Plug it in when you're not using it and whenever you're driving. You'll be fine. I know it's not the best solution, but this thing's got a bit of meat behind it it's got to drive and that's going to pull the battery down quite a bit.
Just my US$0.02