Going way beyond cell cite locator information:

Every time an iPhone user closes out of the built-in mapping application, the phone snaps a screenshot and stores it. Savvy law-enforcement agents armed with search warrants could use those snapshots to see if a suspect is lying about whereabouts during a crime.

The photos you take:

iPhone photos are embedded with GEO tags and identifying information, meaning that photos posted online might not only include GPS coordinates of where the picture was taken, but also the serial number of the phone that took it.

The photos you post online:

Photos posted online might not only include GPS coordinates of where the picture was taken, but also the serial number of the phone that took it.

Your browser history, which Apple uses to assist advertisers in targeting you: Even when you delete it, the phone retains information in the database. Much of it is in screenshots you don't even know are taken:

Just as users can take and store a picture of their iPhone's screen, the phone itself automatically shoots and stores hundreds of such images as people close out one application to use another.

"Those screen snapshots can contain images of e-mails or proof of activities that might be inculpatory, or exculpatory," Minor said.

When you use location services, like to find a restaurant, the phone is capturing your GPS coordinates.

Here's a reason to turn off the auto-correct typing feature:

"The iPhone logs everything that you type in to learn autocorrect" so that it can correct a user's typing mistakes.

Apple doesn't store that cache very securely... so someone with know-how could recover months of typing in the order that it was typed, even if the e-mail or text it was part of has long since been deleted.

Is all this legal? Given the information that's obtainable, ex-hacker Zdziarski cautions that cops should get a search warrant properly advising the judge of the information that's available in the iPhone. "[H]e instructs them to add iPhone-specific language to the warrant."

Mr. Zdziarki's website contains more information on what he teaches cops to retrieve. He has a handy list here.