[pilif]

Well. If you are near an access point apple knows about or just by geolocating your IP address, the iPhone can still download datapoints from that central database that allow it to quickly locate you.

That file on the iphone is just a local copy of the relevant parts of the central database.

Sure. It might be 10 seconds instead of one second now, but that's a reasonable tradeoff compared to the huge log it currently makes. IMHO.

[pieter]

Point is that he's turning roaming off, and probably doesn't have access to WiFi in the foreign city. By having the database, you don't need a data connection at all, thus saving money.

[seabee]

He had to connect to the internet in the foreign city at least once before. The difference is now it must be every time.

[wlesieutre]

Right, but if you travel there semi-frequently, it would be nice to not pay for it each time. Cheap relative to the airfare, but every bit helps.