The people at Bits From Bytes, who sell 3D printer kits, fed some mashed potatoes to a RapMan printer and used it to print some quite credible prototype 3D food.
But it's not without some issues. In the video they indicate the syringe-like extruder is running at a slow 16mm/sec rate, perhaps the slowest typical setting for printing plastic. They are unsure whether this can be increased, meaning food prints (of at least potatoes) are destined for slow production.3D Printing Potatoes With The RapMan (Thanks, Kerry!)
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.