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.
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?
