For almost the last decade, desktop 3D printing has, at its heart, been centered around 8-bit microcontrollers. The ATmegas and other Atmel chips are good enough to move a few steppers and squirt some plastic. With faster processors, you get smoother acceleration, leading to better prints. Modern ARM devices have a lot of peripherals, allowing for onboard WiFi and Ethernet connectivity. The future is 32-bit print controllers.
Right now there are a few 32-bit controllers, from the very weird, out-of-nowhere controller for the Monoprice Mini 3D printer to the more traditional SmoothieBoard. Only one of these boards has the open hardware cred for a proper 3D printer controller, and a this year’s Maker Faire, Cohesion3D introduced a few machine control boards built on top of Smoothie that add a few interesting features and techniques.