Update: Apple has posted a Q&A page with information about the data in question, exactly what that data is, and changes they have planned.

This is, well... it's at least very interesting. Which is to say, it’s something that has to make you wonder: Even when core location tracking is not active, apparently your iOS4 device is keeping a log of everywhere it goes. Which is to say, everywhere it goes with you.

The four images here are a visualization of the info harvested from my own iPad, retrieved automatically from a iTunes backup of my iPad on my Mac (click on each of the images to view full-size). I should note that the locations are actually displayed in a less accurate fashion (visually) by the program that generates the map plots, so as to somewhat avoid any issues and abuse associated with exact location tracking. The information in the data file being analyzed is substantially more accurate and detailed.

From cell tower triangulation (it appears this is where the data comes from), you can see a cross country trip I took with a friend from New York to New Mexico, visits to the Denver/Boulder area, and of course a whole slew of travel around the Pacific northwest, where I live.

Also of interest is that I very recently (within the past two months) had my iPad replaced when the sync jack went bad, yet much of the data is from the old iPad in addition to the new one. Obviously when I restored a backup on the old one to the new one, the data was retained as part of the restore. Interesting. Also, there's location info that's recorded on mine, and in some cases I don't see the location data for areas I know I have been to. I'm not completely sure of the rhyme or reason for that.

Video of the two guys who discovered this and created the visualization program is here. They discuss how this was discovered and go into some detail about the data, where it lives and what they found. Video is via the Where 2.0 conference.

Got a 3G iPhone or iPad? You can run the "iPhone Tracker" app on your own Mac and see what your iTunes backup has sitting around on your computer. If your iTunes backups are encrypted (not a default setting) the data is still there but it's not readable.

On it's face and in isolation this is not exactly a huge deal. The location data is not being sent anywhere as far as we know. It resides on your iPad or iPhone (3G models) and on your computer where you sync to iTunes. Well, that's assuming you don't sync to someone else's computer, of course. In that case, they might have your location data available to view and play with.

And really, that's why this could be a big deal, on some level. And it's not just that the data is being collected, cataloged, stored and exists, it's that it's been there since iOS4 was released, and we didn't know because no one really noticed until now. Someone had to get curious, poke around, dig into the data and discover it by accident. Makes you wonder what other info might be hanging around in places we don't know about, eh?

Hopefully Apple will explain exactly what all the data is, why it's there and how it's used - in great detail. It can't be there for no reason, and I can think of a few cool reasons for collecting the data, but unencrypted and no notification of tracking is a little concerning to me. I'm looking forward to hearing from Apple to understand more.