Why are images saved from Mail and Safari (or screenshots taken on the device) placed into the Camera Roll in iOS?

The Camera Roll album in the Photos application should contain the photos of people, places, and things you’ve photographed – not images saved from within the device (especially the screenshots taken with it).

With iOS 5 you can create albums on the device for images you save, or screenshots you take, but they’ll still show up in the Camera Roll.

It’s a bit annoying that the screenshots I take for work purposes (often containing sensitive information) show up in the camera roll that I jump to when showing a friend a photo I’ve taken.