A) Thats dangerous, with little kids running around everywhere these days. Also what about various other obstacles that can arise?
B) Any moron can park into that space, I want to see that car maneuver itself into a NYC parking spot.
C) The cost of a unit like that would be ridiculous, especially if you consider how useless it is.
And on the final note, even though the idea is cool, if the guy is so smart he should have entered into DARPA Challenge, instead of making parking "easier"