When I spoke to the Garmin bloke at the Bike show (Birmingham) last yr all I got was a shrug. I'm guessing ti will be 2014, and even then in really limited numbers. Rumour has it they've had serious quality control issues and multiple unit failures, enough problems to make it a really bad idea to release them.
I wouldn't be all that surprised to learn they eventually ditch the project altogether, it's almost become a bad joke. To recover the R&D costs they will have to make the cost quite high, probably higher than some of the new solutions coming to market (and the same as well proven solutions), which will make it REALLY unattractive.