Its a bit lengthy, but its a good video on the "how it works" of 3 d printing. On a different video I watched, the commentator raised the thought of "imagine when a neighbor can print a 3 d printer for his neighbors"... The idea being, once everybody has one of these things, it will turn a fair bit of our economy (as we know it today) on its head. Need something? Drive to walmart and buy it? Nope. Download a file. Press print.
I'd imagine in a few more years (if its not already out there) stronger plastics will be available. A two part epoxy blend as the base plastic is melted? Dunno, but its really fascinating to me. Till I saw this, I was really starting to feel like technology had it a plateau, but this is cool stuff. ;)
OhmEye's Introduction and Orientation for 3D Printing with the Reprap Prusa Mendel (http://www.youtube.com/watch?v=B3D56IpACME#ws)