The article's second killer app is an iPhone location feature that simplifies the current Find My iPhone system that can track down a missing device anywhere in the world.

ENGADGET: Editorial: iWatch app speculation is filler, not killer

Mr. Lewis, the data forensic expert in New York, says he recently worked on one case where the spouse enabled the "find my phone" software on all of her family's smartphones, which lets you pinpoint the location of the phone using GPS. She quickly learned of her husband's frequent trips to an ATM, where he withdrew cash she didn't know about.

WSJ: Hiding Money From Your Spouse Has Gotten a Lot Harder