Stratasys has developed a new smoothing station for smoothing the surface of 3D printed parts. This looks like it will produce better results than using acetone or sanding and coating with clear spray enamel. On the downside it looks like it requires compressed air and an air exhaust system so you don't die of industrial solvents. The MSDS as usual is scary and suggests that you do not want to be near this stuff without a respirator. Also, the dimensional accuracy of the smoothed parts is currently unspecified. On the other hand, smooth parts are pretty awesome.