Google's Project Glass wasn't a one off thing you thought it was till we see in the next couple of years again. The company has just been granted three patents that could provide some more clues about the guts behind the augmented reality specs.
Two of the patents are "Multi use eyeglasses with human I/O interface embedded" and "Ambient light display and system for displaying data". The first one refers to the system we have already seen, and the second is the nuts and bolts behind the futuristic eyewear.
However, this one also has a drawing of a heads-up display inside a helmet, indicating that Google probably has plans for its glasses beyond consumer-end use, perhaps in military or police operations.
The other is for a "cell phone display that clips into eyeglasses," meaning the technology could work with prescription lenses as well.