Steve Jobs famously re-leased his SLK every 6 months and never put plates on it -- seems like a great way to avoid this type of tracking if you're in the financial position to do so.
OR, you can simply not put the plates on and blend in with all the other new cars -- and there's no shortage of new cars in the Bay Area. Usually, the dealer has placed their own cardboard/paper license plate with their own company logo in its place. When I bought a new car, I just flipped it around so it was just plain white.
As long as your car is a late model and reasonably clean, with the registration stuck to the windshield, cops probably won't bother pulling you over. Parking tickets may still be issued from the VIN. If you are pulled over, you might get a dressing down and a fix-it ticket to put your plates on within x days. You can do this for as long as you'd like to press your luck.
Apparently you do get a bar code (according to one 2005 article), so the exemption would be of no use against automated readers. It just keeps ordinary citizens from being able to identify your car.
[1] http://pictures.dealer.com/m/mercedesbenzoftampa/1069/537b8d... [2] http://bimmerboard.com/members/q/original/VIN%20located%20be... [3] http://www.m3forum.net/m3forum/showpost.php?p=3856500&postco...