How to use iPhone camera as MacBook Pro iSight?
There was once a project called iPhoneCam which allowed you to stream your iPhone video over WiFi to your Mac, but it seems like this project never got released. 

However, there is an app called Peephole ($0,99) which, according to their support pages, will do the following:


  Peephole for the iPhone is a unique iPhone application that lets you
  use your iPhone as a wireless remote webcam


I haven't tested it myself, so I don't know for sure if it will work. But it should do the trick according to the developers.