See http://carbon3d.com/ for the slick presentation and http://www.sciencemag.org/content/347/6228/1349.abstract for the juicy details.

The main innovation is allowing curing whilst submerged by using an oxygen permeable membrane. This allows continuous curing, which creates really high quality plastics - supposedly equivalent to injection moulds, really high resolution models - high enough to generate smooth slants, and really fast print times - over an order of magnitude improvement.