Anyone Remember Von Neumann Machines?

The New Scientist is proposing that we should send autonomous machines to the moon as a prelude to colonization. These robots would wander around, building solar cells from materials found in the lunar soil. Lunar soil conveniently has all the elements necessary to build solar cells. When the first colonists arrived, they would find a ready made power supply.

The article doesn't show much imagination. With only a little more wishful thinking, we could send primitive Von Neumann machines that would not only build the solar cells, they would also build more of themselves. Physicist Frank Tipler extrapolates that the absence of such devices answers Fermi's paradox, inferring that "We are the only intelligent life within a billion light-years." Otherwise we would be knee deep in the little buggers. Of course, Von Neumann machines can be dangerous.