Antisec hackers, an offshoot of sorts from hacktivist group Anonymous, claim to have hacked the laptop of FBI agent Christopher Stangl, who the FBI has put in recruitment videos looking to hire "cyber security experts." Hackers claimed to have found a .csv file with "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 group has released 1,000,001 UDIDs and APNS tokens to confirm that the data they are talking about is real, though they did strip out the personal information. Some have speculated that they may have even captured personal information from the President of the United States, but that has not been confirmed by the White House.
What we do not know is why this FBI agent had all this information and how he got access to it. Did Apple give it to him voluntarily or did the FBI obtain it in an independent and potentially unlawful way (for example, without a court order). These are the questions the FBI and Apple need to answer.