Another candidate has been added to the list of potential names for Sony's motion controller. Yesterday, Sony filed a European trademark, for use with a control device, for "PlayStation Move." It sounds fitting for a motion controller! (It's application number 008936544 in the European trademark database, if you'd like to see it in its native habitat.)
In addition to that trademark, NeoGAFfer gofreak found another trademark for the logo seen here, which looks more like an A for Arc than an M for Move. We have yet to verify the image ourselves in the trademark database, however.
In any case, we're likely to find out more about whatever this thing is called during GDC.