Universal machines / replicators are cool.
Early prototypes of things that will be better in a few generations are cool.
However, Fab@Home and RepRap are sad, and make my embarassed for them.
I posted a longer rant to BoingBoing a while back:
http://www.boingboing.net/2008/06/04/reprap-universal-con.ht...
I'm hugely interested in self replicating machinery, metalworking, and other forms of constructing items (I launched SmartFlix based on these interests).
...and I've done a fair bit of reading on RepRap (I was considering building one a year or so back).
I am dramatically underwhelmed.
The construction is shoddy, the technique (basically hot-glue extrusion of thermoplastics) is hackish and has poor tolerances, the concept of "self replication" is grossly dumbed down (a very very large number of parts are not constructed, even from high quality inputs, but just store bought), etc., etc.
In short, I was fairly embarrassed for the RepRap folks.
Their toy is somewhat cool (although nowhere near as cool as, say, the Gingery lathe that is cast from aluminum melted in a cast iron cookpot, and machines itself as construction progresses), but to claim that it represents any important step forward in self replication ...