Update (2011-05-12): the answer is no, it’s a Navteq 3D mapping car with a LIDAR array. Thanks to Darrell Kresge for the clarification.
As I was walking to lunch today, I caught sight of this weird contraption, and had just enough presence of mind to grab a few snaps of it.
One strange feature is a spinning white cylinder inside the arm canted at a 45 degree angle.
It doesn’t look like any of the Google Street View vehicles captured before, nor does it have the Google markings. The Michigan license plate is a bit odd as well. A prototype, perhaps? Or is some other company is getting into this racket, perhaps Microsoft?