http://consumerist.com/2012/09/hackers-claim-fbi-has-tracking-information-for-12-million-iphones-and-ipads.html
Quote:Hackers Claim FBI Has Tracking Information For 12 Million iPhones And iPads
Yesterday, while many of us were grilling various meats and dreading the inevitable return to work, hackers posted what they claim are 1 million unique identifiers for iPads and iPhones. According to the hackers, the source of this information is a significantly larger database held by the FBI.
The pastebin post linking to the leaked information claims that during the second week of March, hackers were able to breach a notebook belonging to a FBI agent based out of New York City.
From the post:
"[D]uring the shell session some files were downloaded from his Desktop folder one of them with the name of 'NCFTA_iOS_devices_intel.csv' turned to be a list of 12,367,232 Apple iOS devices including Unique Device Identifiers (UDID), user names, name of device, type of device, Apple Push Notification Service tokens, zipcodes, cellphone numbers, addresses, etc. the personal details fields referring to people appears many times empty leaving the whole list incompleted on many parts. no other file on the same folder makes mention about this list or its purpose."
All iOS devices are associated with a UDID, intended to allow for easier tracking by developers and advertisers. Apple has come under fire in recent months after it was revealed that some third parties were receiving this tracking information without consent.
More at the link.
On their Facebook page they also give a link for checking to see if your device is one of the IDs that was posted by the hacker group. I don't advise using it at the moment since it is not an Apple-affiliated website and you don't know who or what is doing or being done with the info you give them.
How to check if yours is one of them:
http://thenextweb.com/apple/2012/09/04/heres-check-apple-device-udid-compromised-antisec-leak/