BrainPort – Help for the Blind
The multiple channels that carry sensory information to the brain, from the eyes, ears and skin, for instance, are set up in a similar manner to perform similar activities. All sensory information sent to the brain is carried by nerve fibers in the form of patterns of impulses, and the impulses end up in the different sensory centers of the brain for interpretation. To substitute one sensory input channel for another, you need to correctly encode the nerve signals for the sensory event and send them to the brain through the alternate channel.

The brain appears to be flexible when it comes to interpreting sensory input. You can train it to read input from, say, the tactile channel, as visual or balance information, and to act on it accordingly. In JS Online's "Device may be new pathway to the brain," University of Wisconsin biomedical engineer and BrainPort technology co-inventor Mitch Tyler states, "It's a great mystery as to how that process takes place, but the brain can do it if you give it the right information."

Link with more information: (if link below doesn't work - cut and paste)
http://science.howstuffworks.com/ref/brainport.htm?cid=s19