Lots of people use a Raspberry pi running Octoprint to control their printer... (think 3d print server) you still need a reprap controller such as ramps, rambo, rumba, duet, smoothieboard etc to actually control the machine
There are highly experimental (read that as insane!) machines running directly on a rpi, but to comes down to the OS fighting with the real time requirements of a bare metal controller. (a microsecond delay as the OS is doing something unneeded for printing produces a blob in the print)
Edited 1 time(s). Last edit at 12/30/2015 11:25PM by Dust.