Epson has succeeded in printing an ultra-thin multilayer circuit board using special conductive andinsulating inks.
There is even aPrinted Electronics 2004 conference planned for early December.
Totally unrelated in many ways, but still on the subject of PCBs, is the small but apparently growing trend, coming, as far as I understand it, out of the amateur radio community, of hobbyist PCBs. There are many firms which will print them for you, and even instructions on how to print them yourself in your kitchen. See also the Printed Circuit Making for Hobbyists FAQ(in Word format; see the Google cache version if your computer doesn't do Word).