Have you ever seen that episode of CSI or Law and Order where they catch the murderer by determining when he/she used his/her hotel key to enter or exit the room? The murderer says that they were "in their room all night", but the electronic key/lock mechanism tracks when the door was opened and closed, and it always seems to fall around the time when the victim was killed.
Why can't hotels apply that method in the real world to determine if a guest is still in their room in the morning to perform their daily housekeeping? How difficult would it be for the head housekeeper to have a blackberry that syncs to the central hotel key computer system, and alert him/her when a guest exits their room in the morning? Why should I as a guest either a) be woken up by a housekeeper simply trying to do her job, or b) feel the need to alert the person they are entering the room when I am getting in or out of the shower?
It seems to me that the hotel industry is missing a really, really simple way to satisfy customers who are staying at their hotels for more than one night ... or even the people that want to sleep in until the exact moment of checkout.