I personally didn't think much of this law, which appears to be implicitly linking a health hazard with cell phone radiation in spite of a paucity of data on the subject.
Now things have gotten more interesting.
The CTIA -- the Cellular Telephone Industries Association, a mobile phone trade association -- has weighed in with a lawsuit against the city [PDF link]. Specifically, they've filed a suit in federal court claiming that the law seeks to supersede FCC authority on regulating radio emissions. More importantly, perhaps, the suit contends that the law confuses consumers by implying that lower radiation levels are safer -- a completely unsubstantiated assertion.
I don't generally find myself siding with trade associations, but this is exactly the point I was making in the original post. This sort of law encourages a superstitious wariness of technology, and it's ultimately bad for the entire technology industry.