I wonder if they can print without using support structures? I would have expected layer bonding to be an issue due to no gravity, but if it's really not a problem (as indicated in the article), I think that 3D printing should work better in space.
As for layer/bed adhesion. Even here on Earth, the RepRap MendelMax/Lulzbot [1] can print upside down. I imagine that's true for most of the units made from aluminum extrusions. And there have already been prints done in parabolic 'zero-g' flights using a Makerbot looking printer [2].
[1] http://download.lulzbot.com/TAZ/photos/upside_down/Lulzbot_p...