Printrbot has just came out with a new 3D Printer model. Brook Drumm just made a new version of the PLAY. Play V2. He made a decision to return to a machine that can be hacked by it's users.
Of course the important thing to this forum is that it includes a Raspberry Pi mounting. This is a B+ mount format. This allows built in support for a WiFi server like Repetier server or Octoprint, plus a few others. So not only can it run untethered it can also slice objects for printing. This allows web based operation from smart phones and tablets.
Available as a kit, assembled and a future version for upgrading the earlier version of Play. No word as to powering options from the printers PSU.
NOTE: Printrbot's CNC V2 also is designed to incorporate a Raspberry Pi into the control system. Not sure what it's role is. These are not the first Raspberry Pi friendly products from Printrbot. They offered Raspberry Pi version 1's for early products.