Two things. First, if Arrington can produce the physical prototype that TC developed on its own, that would be a big deal to me. But he'd still have to establish that the device Fusion Garage is producing used IP from their prototype.

Second, I can see this happening. Arrington has an idea for a tablet. He comes up with the basic idea and rough specs. Fusion Garage goes and implements it. In Arrington's view, the device is partly his because he had the original idea. In Fusion Garage's view, the device is all theirs because they did all of the work to create it. Both think the device is "theirs" because they underestimate the contribution of the other.

Arrginton really needs to establish what exactly they did, and demonstrate that it made it into the final device. I'm not sure what his actual contributions are from the claim; coming up with the specs isn't a big deal to me. (Note I'm talking morally and ethically, not legally - as always, I am not a lawyer.)