Yes 'interested_party' of course you can do it via the cellular network, but then you'd have to make a deal with the providers and they might get in trouble either legally or socially and want money, so to simply sit on the street with your BT computer setup is much simpler and harder to complain about and cheaper.
Incidentally, I remind you that several shopingcenters now do experimental statistical tracking of people's movement using the signals of their cellphones as medium, they dare because there's money in it, and theoretically shoppingcenters are private property and they claim it's not personalised.

Your face is a pretty well indicator of your position.... let s all wear a mask, to stay annomymous....
for BT, the specifications says that discovery mode got to be OFF by default. If your turn on discovery, you take off the mask ...
I am in London right now, I am more concern by the cameras in the streets than I am about my MAC address of my cellphone.
May be the privacy people can try to focus on something that really matter?

who?

They had to count them all?
Now they know how many holes it takes to fill the prince Albert Hall!

We ween there are more fools pass through Gotham than remain in it!

Wise men of Gotham (known as Gothammites)
Went to bowl in a sea...
Err, one dark knight!

This morning it's Bath, and Skynet by tea'oclock.
Who are you going to call now, super friends?

This is not a bat detector, per se. To think an agent of chaos who wears a fancy dress costume, can rob us of our half and half? Using sonar to see? Just like a... submarine; to image any place where there’s a cellphone. Orange you glad, Gordonly nose, heavin help when that which we seek to destroy, becomes us. Hang on Snoopy! It's not enough that you track my cards; my likes; where I surf; who and what I'm on about a good talking to; my image, signature and spital; but now you've also got to "see" over my elbow to get to me arse? Go on and take the apple cake too!

Now that's want I'm talking about!
Spying on 30 million people is not part of my job description! And that's the Bluetooth of it. It got drunk and now it's got a hangover. What IS is. Darwin must have been compulsive for liar.

A a thousand points of light, a thousand security specialists, the hole lot of whom needs to lay off the tea-fiend. Akk for a bobby-shtick bludgeoning business? Every little helps puts Florence and Fred into avoidance schemes from the 
Best Of British Johnny! Cock-up Mates, this is our finest inclusive offer. Maybe it's time you shared your secret
manoeuvres. This is your blu-jacked life, go on and give it a ping. Four thousand holes in Blackburn, Lancashire! It looks as if The Rovers will be found out on roaming chargers!

so why not just track that transmitter instead?

Can't they use triangulation with the phone's transmitter to track users?

What data does a phone transmit, can that be utilisied as a partially/fully unique ID?

How are they going to use this tech to make money?

If you're stupid enough to leave your phone permanently visible to all via Bluetooth, you really have no cause to complain about anything stemming from that.

Be it: blue-jacking, viruses, rude names trying to connect, poor battery performance or alleged Big Brother tracking schemes etc.

Don't most people turn off BT? almost nobody uses BT headsets (and still very few car-sets, at least over here) and without them BT just drains the battery so people leave it off.

To keane: yeah to regular normal behaving BT devices, but as long as you send out a signal a technical adept person can track it.

This kind of trick has been on the cards since bluetooth started appearing in phones.
Simple solution though - keep it hidden except to your own devices, or turn it off...

I'm still working on my device that scrambles CCTV camera feeds... ;)

Bluetooth, for all the hype that it gets, is an old technology that keeps getting resuscitated by the same companies that designed the original. Bluetooth was meant to replace wires at a time when security was not such a big deal, now that every shmuck and script kiddie out there thinks he's a hacker, every unsuspecting passerby is a "target" because now their phone, their sunglasses, and eventually their wallet is Bluetooth enabled so when their head and their ass come together, they'll still be able to take that call. 
You can still find devices that aren't discoverable, just use a brute force scanner, not being discoverable doesn't mean you're safe, the only way is to turn it off, or buy a phone that doesn't come with it. All we need is Big Brother figuring out that they can track every citizen with Bluetooth, but they probably already know that....

My phone is only visible to other Bluetooth devices when I tell it to be. In fact all the LG phones I’ve ever used that had Bluetooth were like that.