My supposition is that some of the phones that are now in customers' hands were initially in the VZW employees hands (I was told by at least 2 different VZW CSRs that they had the phone around to play with for over a week before release).
A lot of people here have noticed that the battery has lasted a lot longer after they have let the phone completely die once or twice and then charged it fully. I know that it has made a difference for me as well - I went from getting 7+ hours to well over 12 b/c I am not actively on the phone much when I have a computer with fast Internet access like I do at home, so you could always try that. Be warned, though, YMMV.