Cell phone charger locator

I have a tendancy to forget where I put stuff in my house, especially when I use things in places I normally don't- I usually charge my phone in my bedroom, but on some occasions I plug it in somewhere else- then I take the phone, and then I cant find the charger when I get back.

Now, every cell phone charger I've ever seen has either a cradle (I wish more phones used these) or a "box/block plug" so it shouldn't be too hard to intergrate some sort of short range transmitter, that can communicate with the phone in most houses or small buildings, and a speaker that can make a beeping sound, into the box.

The plug would still look somewhat like an ordinary cell phone charger, but with one little button on it somewhere, and a grill or grate for the speaker. The charger, itself, would have rechargeable batteries inside, because if you lost your charger, it's probably not plugged in, unless your outlet is behind a desk and the cord slipped down. The charger will cease to beep upon being plugged into a phone or the button being pressed, or after about a minute. If the button is already pressed down when the charger is signalled to beep, it would still beep, just in case the button was being pushed down in a bag or it was jammed/broken.

As for the phone, I don't think that this would be too complex- I don't know the reliable operating range of bluetooth, but if it's long enough to get a signal at least 1 floor directly above/below, it'd be good enough- if you were any further away than that, you probably wouldnt hear it :) so this could in theory use technology that has already been in the majority of cell phones for a few years now, and is becoming more and more common. If the phone has bluetooth, then all that would be needed was support from the phone's system software.

The charger would be more expensive, though, with bluetooth, a speaker and rechargeable batteries, so while this could, in theory, be a pack-in with a phone that supports "charger paging" there would probably have to be a "normal" charger that also can "just" charge the phone, also available for seperate purchase. although this pageable charger would also be sold seperately obviously, the phone companies would end up in a lot of hot water if they didn't offer a "regular" charger that also worked with the phone, because not everyone is going to want to spend that much money for that feature if their original charger broke and they need a new one.