The story broke today that everyone's iPhone is keeping a log of everywhere they have been. This is a pretty scary undocumented feature. I downloaded the application that displays everywhere your iPhone has been and sure enough here it is:
I would imagine a few things will happen soon. First of all, Apple will remove this feature in a future version of iTunes or iPhone iOS (BTW, iPad 3Gs store this info too). I also expect that there will be some pretty cool apps that will come out that provides even more details. For example, where was the phone last Tuesday at 8PM. I suspect there may be some nervous spouses out there.