I believe there are a bunch of people quietly working on systems based on LinuxCNC. See http://toybuilderlabs.com/blog/2013/6/1/beaglebone-driven-3d-printer for example.
actually I’m waiting for this…https://groups.google.com/forum/#!searchin/deltabot/due/deltabot/IzU-5FoKctk/SsPaemJnhP0J