Similarly, what if the UDIDs are from people who installed a common app on their devices and agreed as part of the terms and conditions to allow information about their hardware (including device name, UDID, etc.) to be transmitted to the app vendor and to other parties including law enforcement?
EDIT: the question of whether they should have this information is completely separate from whether it's illegal for them to have this information. And, as noted by others, no proof has been presented that it was obtained from the FBI.
Huh? How? Most companies who have an iOS app with over 12 million users could have given it.
The paranoia on these UDID threads is ridiculous. Investigating crimes is what the FBI primarily does, so if they've got any information it's most likely for that - not some broad-spread domestic surveillance scheme.