Because Adobe can't be the only mad scientists of media manipulation, a group of PhD students from the University of Illinois at Urbana-Champaign have devised a method to realistically insert synthetic (read: fake) objects into a photograph with "proper perspective, occlusion, and re-lit with an estimated lighting model of the scene's illumination." On the front-end, users draw a bounding box to set the scene, highlight sources of light and foreground / blocking objects, and that's apparently about it. Translucent objects seem to work, as well!
Not that you needed more of a reason to be an internet cynic - a disbeliever of all unbelievable photography with just a touch too much lens flare across the eye of the flying dragon that invaded New York in the summer of '02. (Don't remember? Clear documentation and accounts of the day are assuredly all over Reddit.) According to the group's research, user studies show both ease of use with the UI and an inability to easily distinguish real from rendered pictures. See it for yourself in both the pictures and impressive video below. "Render Synthetic Objects into Legacy Photographs" is set to be presented at SIGGRAPH Asia 2011 in mid-December.