Here's a message I posted back in June on Bluetooth security:
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SUBJ: Bluetooth = Blackcloud
FROM: incognito

What is being proposed in Bluetooth is shortsighted. To create a standardized protocol that can be controlled by anyone within an obscured 25 meter radii is extremely foolish. Its counter to basic security as it removes one very important layer: physical access. If you don't need to even go through locked doors to affect things within, then part of your security has evaporated without your notice.

Before you tell me that bluetooth appliances are noncritcal devices and can do no harm, think about the angry employee that drives by during a long holiday and remotely turns on all the empty coffee machines? There will be more than a yule log burning when everyone returns from holiday.

I made a theoretical wager in our lab that illuminates the basic problem:

"Once Bluetooth is widely adopted into products in about four years... I could ride an elevator from the bottom to the top floor of a highrise office building with a Bluetooth Sniffer-Interrogator inside a briefcase and return with enough information to create havoc."

Hackers will love your Bluetooth implementations. You'll give their mischief physical muscle its never had before. A simple palmtop will be able to sniff out your bluetooth telemetry packets and start uploading false telemetry setting off alarms. How are you going to program against that and more importantly, how are you going to convince your customer that THAT is the problem and not a firmware bug in your product?

bad idea...