On their blog, Romotive has made public which audio waves you need to generate on which audio channel to control a Romo first revision smartphone robot. So if you want something programmable with an audio port to control one, now you know how!
The article even briefly mentions my own work on a Romo control library for Windows Phone, which can change the amplitude of the soundwaves it sends out to control robot speed as well.
This library (and my first two apps) are slowly but surely nearing a state in which they can be made public for every WP7 developer to easily interact with Romo devices. The Romotive staff has already received preliminary XAP files to use on the Nokia Lumia 800 they have, and they told me they liked what they saw so far.
There should be more information about this soon, even though the next revision of Romo (which should be out in or shortly after this Februari) will include more frequencies as part of the interface.
Just be patient...