It seems like it wouldn't be really that hard, even given the whole "gravity" issue. From what the article said, it will use spools of plastic, which I assume means the printer is similar to a Makerbot. A Makerbot melts plastic from a spool and lays it down in rows, kind of weaving the molten plastic together so that it solidifies into one solid shape. The spigot just extrudes the plastic, and the platform also moves up and down with the model, so as long as the model is securely attached to the base, there shouldn't be any problems.
That said, I really do want to see a video of it!