A few weeks ago (in September, I think), David and Eric stopped by for a tour of my local makerspace in Boston, Artisan's Asylum. I've been working on an open source hardware Linux board called the Rascal. It's like the Beaglebone, but it works with Arduino shields. David and Eric suggested that I should post something here alerting your group to the existence of the Rascal. I think they liked that it had an onboard Python editor and web-interface.
My impression is that the OpenROV is using the Beaglebone, which seems like a decent choice to me. I think David and Eric thought there might be people who wanted to modify their ROVs to do other stuff with Arduino shields.
Anyway, here it is: http://rascalmicro.com
Somerville, MA, USA