This is the stated reason for the release - to have people ask why an agent has 12m UDID numbers on his laptop. They released 1m out of the 12m UDIDs so that they can guarantee a statistical sample that can be verified, while preserving a bit of privacy.

Along with the UDIDs were other columns with an assortment of personal data, although there were a lot of holes.

How large would a 12m line long .csv file be?

Not sure how many bytes per entry, but it would be of the order of gigabytes.

It would probably compress well

The 1,000,001 line file is 136MBs uncompressed, so 12M should be around 1.6GB

It might be a gigabyte if there were about 90 characters per line 1 or 2 gigabytes tops? "on the order of gigabytes" is a rather pretentious way of saying that.

The filename refers to NCFTA, which might seem in context to be http://www.ncfta.net — perhaps some bit of intel that's widely-traded in NCFTA circles for various uses? I mean, hey, pretty useful if you're tracking down pretty much anything in which an Apple device is used, right?

Perhaps Apple (or someone) is having them do an investigation:

http://www.forbes.com/sites/kashmirhill/2012/04/26/the-fbi-w...

exactly