The LA Times recently ran an news story about researchers at the University of Washington who have found a way to use nanotechnology to put customized displays on contact lenses. Right now, the technology is very basic (a contact lens can display a red dot and a blue dot) but there are practical uses, like health readouts. The article mentioned the researchers are looking for ways to monitor glucose levels, which is important for diabetics. The eye contains a lot of health information so a contact medical device that would display vital information is very helpful, in theory. Eventually, entire computer screens could possibly be displayed.
It all sounds like something out of a science fiction novel, but human trials a long ways off. The eyes are a delicate and sensitive part of the body so any new technology related to contact lens wear needs to be rigorously tested first.