[alain94040]

You do realize that the towers themselves have had that information about you forever, so AT&T (or now Verizon) can plot your every move.

[davidw]

Which can be a good thing, if, say, you get kidnapped, or someone gets murdered and they're trying to retrace their steps. What's not a good thing is if there's no one "watching the watchers".

[jws]

Does AT&T retain the data for a year? Do they give it to the ass hat that stole my laptop?

[allwein]

The iPhone only maintains the last time a given cell tower was "seen". It does not have your complete movement data for the entire year.

(Exception would be someone that has been traveling the entire year and has never been back to the same place twice.)