http://www.deviantart.com/view/33403033/
the description is in portuguese, of course, i'm brazilian...
so, i will translate the essence of it: done in cinema 4d, no photoshop at all... got the guitar model from some model library, probably from 3dcafe...
just used some crazyness, played with materials, tried to make a nice velvetish stuff and a nice goldish material
the used HDRI plus a omni light for illumination... took 7 hours and a half to render o.O i think i put the settings too high...
hugz