Seems to be hot at the moment. Although, in my opinion, its too close to .com and causes a higher amount of confusion as a result. Its just too similar.
I have a .com and a large business chose to go the cheaper route and get and the .Co....As a result my catch all mailbox, of the. Com, fills with both employees and customers making the error. Its a subliminal error. It can't be corrected. There's nothing a business can do to fix it except buy the .com...