Meanwhile, the FCC's enforcement chief just put out a press release decrying cell/GPS jammers saying they "create safety risks".
http://www.fcc.gov/Daily_Releases/Daily_Business/2011/db0209...
http://www.fcc.gov/Daily_Releases/Daily_Business/2011/db0209...
(I've never heard of a good reason to block cell phone transmissions. It always seems to come down to trying to enforce some vision of politeness via technical means, which doesn't take considerate cell phone usage into account at all.)
You could (presumably) attempt to fix this with technology. It might even work for a while, but when it breaks, someone could very easily die. And they'd have died of someone else's dislike for cell phones, which is not a good reason.