The controller includes H-bridges, MOSFET drivers, RS485, thermistor circuit, and lots of little niceties. While currently offered only as a $30 SMT kit, the impressive assembly how-to makes surface-mount soldering look not so scary.
And printing a circuit board is... just astounding! For all the criticism levied against RepRap's claims of (eventual) self-replication, this step says to me that RepRap has real legs-- it's not just an open source 3D CNC platform with an insane goal. The resulting board functions as an optical end stop for a RepRap-- to Rhys Jones, I offer my humble [APPLAUSE]!!!