Was it really built overnight...maybe close to it. A version of the elf was released to media without the touch functionality and programming. Possibly, the only thing different from that version is the screen and some extra coding. The technology for the screens may have very well existed and implementing an elf sized screen may have been easy to do in a few months.
The programming isnt all THAT great is it? I've seen that all in flash in some form or another and you've all rotated 3D views of phones before and whipped them around rotation. Not far off and not all that hard to do for those who know how to do it. I'm not talking about me...but those who KNOW!
What I'm trying to say is...it is very well possible that the whipped these babies out quickly!