I doubt it's Apple. I checked the list, and there're tons of German people in there too (one can see that by how they named their iPad). I really doubt that the FBI would be interested in tons of German girls, for example (many iPads seem to belong to girls named 'Sandra' (iPad von Sandra)). If Apple were the culprit here, they would have been able to just deliver the UUIDs from people residing in the states (since they know which UUID is connected to which app store).

I hardly think it's Apple that leaked the information. Even if it's hard to believe for some people: Apple values their users' personal information pretty high.

I personally believe that this is from a internal FBI job, so they got this information in a non-legal way.