He makes it sound as though this isn't particularly difficult or expensive. Does anyone want to speculate on the method he is using to compile this data? For his zipcode database he seems to be running mass queries on the Google Maps API.
Simply doing mass WHOIS queries to the regional registrars only gets you data about the corporate headquarters of the ISPs, which I suppose could be enough depending on the level of granularity that is acceptable to you.
(presently a similar question on his forum, posted by someone else, is unanswered: http://blogama.org/node/105)
http://www.maxmind.com/app/geolitecity
I haven't verified that claim.
This is also the frequency at which Maxmind releases updates. So...
Anyway, I'd still like to know what those sources are.
I'm guessing that you're merely pretending not to understand what's being implied, but I don't understand why...
wc -l ip_group_city.csv
1195012 ip_group_city.csv
wc -l GeoLiteCity-Location.csv
238957 GeoLiteCity-Location.csvAkamai has a (much more expensive) geolocation product that's based on doing triangulation, since they have a lot more information on routing (all those edge servers) but I'm not sure it's appreciably more accurate.