Might the WIFI or the touch screen function be turned on? I read somewhere that whenever the stylus is removed from it's resting place the touch screen switches on? Or has the battery been badly charged, is it a production spec battery? Has the power output to the screen been increased in order to make page turns faster?
Wait! Has the backlight been left on?
I'll take it with 4 hours battery life because if I have to wait more I might go have a look at those new MacBooks. Only kidding...