If you push the On* button, and ask them about updates for the myLink system, they will have no idea what you're talking about. At least, the rep I was speaking with had no idea what myLink even is.
I did contact the GM Infotainment department and spoke with Kyle. As of right now, there is no way to update myLink radios. He said they are working on it, but no ETA.
My wife recently got a 2013 Nox, and there are a few extra apps she has on hers, that are not on my '12' myLink. I was hoping to update, but not yet.
Good news is, he mentioned again that they are still working on map apps