New research has proven that your cellphone is a walking ID billboard for hackers. Actually this isn't something that can be patched. It's built in to the network as features. I listened to Steve Gibson explain this this afternoon and was astonished at what he reported. You can listen to the explanation yourself here: Security Now his comments on the vulnerability start at the 14:17 

The story he refers to can be read here:

Researchers Hijack Cell Phone Data, GSM Locations

Here is a little excerpt:

"A lot of this isn't terribly secret, but it's not that well-known," Bailey said. "To find information on users, that was our goal. These pieces of information come from all over. The caller ID database provides a lot of information about people and companies. One thing we found is that we could go through the provider network in a given city and determine which numbers have been allocated to a given company. Using that information, you can leverage some of our attacks and target specific handsets owned by company executives."