I find it strange that Google's self-driving car project appears to be focused on small passenger vehicles, because the technology appears to me to have much more near-term potential in the long-haul trucking market. Self-driving passenger cars, after all, offer buyers the relatively minor convenience of not having to pay attention to the road while riding between urban locations. They also likely improve safety slightly--city driving not being all that dangerous to begin with--at some cost in speed (due to a less aggressive driving style).
Self-driving semis, on the other hand, offer substantial cost savings by eliminating the driver altogether. They likely also improve safety significantly--especially at night, when infrared sensors would surely do much better than sleep-deprived humans--as well as saving considerable time by eliminating rest and meal stops. (For really long trips, truck stops would no doubt be happy to offer filling service for driverless trucks at a tiny fraction of the cost of a full-time driver.)
One can easily imagine companies converting their entire fleet of trucks to driverless models, eliminating their driving staff entirely, and replacing their team of dispatchers with a few driverless truck programmers. Putting aside the technological hurdles--which exist in both markets--it's hard to believe that the commercial trucking market wouldn't be far easier to sell on this concept than even the geekiest first-adopter consumers.