I've just come across the concept of programmable matter from last year's IEEE Computer. The Claytronics project is a joint effort between researchers at Intel and Carnegie Mellon University.
The core concept of programmable matter is nanoscale, programmable, sensing, locomotive entities called catoms (claytronic atoms – not strictly correct; they have more in common with complex cells).
Download the original article: Programmable Matter.
Note this is not a new concept. Nanomorphs were proposed by science fiction writer David Pulver. They have similar properties to claytronics.