I think it's going to take a while before 3D printing at home becomes more than an expensive hobby.
I doubt it's going to revolutionise printing and kickstart home production the way the stamp/pic/avr/arm chips have opened up to the home market in the near future.The price of entry and running is to high at the moment.
What I do expect is it'll stay more like a bureau service for a while, much like the laser etching/cutting and pcb bureaus. The bureaus will have the higher end machines so you get a better quality finish and as long as the turn-around and price are sensible it seems a more likely route for the near future.
I can think of a few things that for myself could be useful printed, but i'm not spending £500-£1000 on a printer to do it. Even then I think the finish will leave a lot to be desired.
Whether they'll become useful mass market devices or just be the printing version of a knitting machine only time will tell.