I have seen this thing at hp labs - and seen the output, though not actually seen it in operation. Very impressive.
It uses support material that is dissolved later, meaning it can print any shape. They had some nice examples of a geared mechanism inside a frame, but printed as a single thing fully assembled.
I suspect you can get as nice with a reprap and a fine nozzle if you tried, but this is much more user friendly from what I could see.
8 colour for $17K is pretty good, though the plastic is no doubt silly expensive.
Not bought one, well, no quite yet :-)
I bet you need a damn windows machine to drive it though.