The "main" part of Sony's motion controller, the wand, is the PlayStation Move. The other part? We originally called it the "sub-controller", but it appears that name was a working title, it's final name being the... Navigation Controller.
Boring, yeah, but then, so was "sub-controller", so at least this is an improvement. And doesn't sound like a character from Thomas The Tank Engine.
The revelation comes from the device's filing with the FCC, which had to disclose its final title. Sadly it didn't also include shots of the Navigation Controller's insides, as Sony opted to lock those down for another six months.