I'd just read Kurzweil's book and I remember saying they'll probably have one by 2010-2011 because smart phones will be the free phones by then. I was right for one simple reason: Most people tend to dismiss new tech right up to when it stops becoming a luxury item. As soon as people find value in something and they can afford it, adoption is practically inevitable.
I hope my self driving car has a nice sleeper option so I can take long road trips and wake up at my destination.