It works by placing a specular screen in front of a bright light source, but the principle is that the light source must be very tiny and very bright, or else you will only get a blurry image. I'm certain that what is really happening is that the resulting point light is emulating the focal point caused by a lens, thus resulting in a clear image.
The prop has my logo on it which can be used as a reference point in aligning the orientation of the projected image. Basically, the logo is on the side of the top of the image. The projector is not intended as an in-scene prop, but rather a source of illumination.
Here are some examples of the projector in action:




As well as a LQ video clip:. http://www.thetagraphics.com/octane/test/!proj1.swf
The gobo image of the rings and the poc file is included. All I ask is that I get credit, and I am interested in seeing what you all do with it. Enjoy!

EDIT: Fixed the video link. Also forgot to mention that to change the projected image, simply replace the image in the Transmission node in the Gel material. If its too dim or too bright, just adjust the emission power of the lamp. Also, in the promos I imported the obj at 50% figure size, in case you're not getting similar results.