At GDC, Sony engineer Gabe Ahn proclaimed that 10 million PlayStation Move units have been shipped to retailers since the motion-control system was released in late 2010.
Yeah, that's "shipped," not necessarily "sold," but we can infer a decent portion of them have at least cleared shelves. Of course, included in that total is the PlayStation Move Navigation Controller, which is basically useless with a move game, except to provide a more ergonomic secondary control and a means of going through menus and selecting options.
Ahn said the figures showed an attachment rate of 1 out of every 6 PS3 owners buying a Move controller. I'm not sure why one of them would buy a Navi controller and not a Move wand. I'm sure many bought both, and still others bought two Move wands and a navi controller. 10 million sounds good next to the 18 million Kinect is reporting, but Kinect is a single device.