I was forwarded this article recently by Tom,

Bluetooth is watching: secret study gives Bath a flavour of Big Brother.

It's a very interesting read, as I have been working on similar things, but just in the lab/office at the moment. However, there is no reason why it cannot be extended to a city wide project.

I find the article is very sensationalist, one person was quoted as saying:

"This is yet another example of moronic use of technology," and "This technology could well become the CCTV of the mobile industry. It would not take much adjustment to make this system a ubiquitous surveillance infrastructure over which we have no control."

Which is very silly in my opinion, the first part I directly disagree with - it is in fact a very clever use of technology, cheap, easy and quite interesting!

The second quote is easy to disagree with, especially "..over which we have no control". Simply turn your Bluetooth device to 'un-discoverable' a settings which I have had on every Bluetooth phone I have owned for the last 5 years. Or of course just switch off Bluetooth altogether!

Strangely enough - I don't see any complaints about the fact that for years it has been possible to triangulate your approximate position (to as near as 1m I believe) from mobile phone cell towers, its just not that widely accessible! This is a technology that can only be made private by switching off your phone AND removing the battery (as I seem to remember reading about some phones still transmit in the OFF setting, but I don't have a reference). Admittedly however, there are stricter privacy rules. Checkout the Orange Location API