One of the most active researchers I know, who goes under the nom de plume Herbbie, has apparently been researching interference lately (I cannot imagine why). At issue is penetrating, or creating, structures that block wireless signals.
On one hand, this is a pain in the neck for people in older parts of town. The metal lath used in old plaster walls creates an effective Faraday cage (see http://online.wsj.com/article/SB126221116097210861.html), and makes it tough to steal your neighbor’s wireless Internet.
On the other hand, a wireless-proof container might be very useful in other situations. Herbbie, obviously thinking of passive-wireless devices, sends me this link to the Passport Stronghold website, marketing a metallic sheath that blocks access to the passport’s RFID tag. Like many ideas, this one is blindingly obvious, and obviously necessary: http://www.passport-stronghold.com/index.html.
And on my third hand, he also passes along this commercial “can-tenna”: http://www.cantenna.com/. I don’t know if it will pierce a chicken-wire Faraday cage, but it’ll darn sure reach a lot farther than next door.