Hi, I just finished my PICgoto telescopic mount controller, it can handle all steppermotor controlled mounts with 12V steppers up to 2.5A. It is an open source project. The PCB layout/design + PIC hex files can be downloaded at http://es.groups.yahoo.com/group/Picgotogroup/
It is in Spanish, but the guys over there also talk English.
I am now busy building a handcontroller, but are thinking about using the RPI for that so I can include a star database.
I already took a test-shot with the control of this system on my NEQ5 mount (fitted with 144 tooth RA wormwheel, 7.5 degr./step steppers and 1:120 reduction). But since the wormwheel number of tooth and reduction factor can be set it can also drive a Losmandy G-11, Vixen GP-DX , HEQ5pro/EQ6pro or even a big Astrotechniek CP-180 mount.
200mmF5/HEQ5pro in backyard observatory. Halley:300mmF3.8 Takahashi Astrograph on CP-180
Under construction: heavy 100kg+ payload ASH mount with Littlefoot Elegance Photo control