I backed the 1Sheeld
(yes that's spelled correctly) on kickstarter and it arrived today. Was very easy to get working, though bluetooth seemed a little unstable with my galaxy S3, but my old S1 worked great.
So the first project was to strap it (haphazardly) to a magician chassis
with an h-bridge IC
and use the Orientation sheeld (that's their name for the virtual shields on the phone) to drive the bot.
. This includes a robot library I've been working on, so far does motor control abstraction for h-bridge and dual-RC-servo and optional speed ramping/smoothing. Feedback and improvements welcome.