I'm not sure creating self-replicating robots is a good idea. What's to limit their rate of replication, especially if they posses self-awareness?
If these replicants can also replicate their own spacecraft, it has been estimated they could spread throughout the galaxy in as little as half a million years. Also, uncontrolled replication could result in these robots using up most of the mass of solar systems for their raw materials.
What would happen if one of these probes entered our solar system and began mining our planets, especially the Earth, for their raw materials?
A good article about all this is here:
http://en.wikipedia....ting_spacecraft