Self Replicating Machines

Can machines reproduce or replicate?  Reproduction implies the ability to mutate and implies evolution. Machines need to replicate, or make new copies of themselves with the same capabilities as the original (typically at the macro level).

See:  Wikipedia entry on Self-replicating machines

This is a very good book on self replication:  Kinematic Self-Replicating Machines (read it on-line).

What happens when we make machines that can replicate (or even reproduce)?

Years ago, I read several of the Berserker SF stories by Fred Saberhagen.  Basically, some race millions of years ago created self-replicating war machines and we discovered them near the center of the galaxy.  It scared me so much that I didn't sleep well for weeks.  

Berserker Fan Site

What are your thoughts on self-replicating machines?

Will this be a problem?

Will this be the next level after the singularity?