It sounds as though to me that he's been awake all but three months since his accident in 1984. From what I'm gathering he's been able to communicate the last 19 years with grunts and blinks, and the breaking news is more his ability to verbally communicate rather than any type of "awakening." The article provided by
Jaime mentions him reacting to an earlier medical bill and to Chevrolet commercials. The family is also reported to have taken him to family functions regularly throughout the nearly two decades he remained silent. I imagine they couldn't give up on somebody they loved when they were able to respond and acknowledge them, albeit limited.
I think it's great that he will be able to communicate better with them now and get to truly know his daughter, who was a mere six weeks old at the time of his accident. The culture shock aside
(detailed extensively) I imagine he'll be glad to participate in the outside world again, and I'm sure his daughter is elated at having the chance to know her father.