There's a huge hacker community out there working with both Arduino and Raspberry Pi for astronomy applications, including interfacing to a GoTo, or even building your own GoTo from scratch using stepper motors, etc.
Raspberry Pi and Arduino are totality different hardware (although similar in size and price), but because they are both so open, and therefore interesting to hackers, it's pretty easy to adapt Arduino hardware to work with Raspberry Pi, and vice versa.
Raspberry Pi has the advantage that it's a fully fledged Linux computer, so it can potentially run any Linux program, whereas with Arduino, there isn't as much available in the way of commercial software, but being fully open source, the hacker communities are more than willing to share their ideas, designs and code.
For Raspberry Pi, try the AstroHub as a starting point:
http://www.raspberrypi.org/forums/vi...15723&p=443964
For Arduino, start with the user forums; e.g.:
http://forum.arduino.cc/index.php?topic=120124.0