Faraday shielding film for windows.
It's not quite as good as a Faraday cage (or better yet, not putting up wireless access points at all) but it'll definitely be on the radar of IT and infosec professionals in the near future thanks to some very high profile network intrusions that used wireless networks as their beachheads: A thin, transparent film that is not only impact resistant, but filters RF emissions, so that signals from outside can't get in, and more importantly, signals inside can't get out. Supposedly, this stuff's been in use on the government side of things for a while now, and it's just been declassified. The article makes it sound like you're going to be able to walk down to CompUSA in a couple of years and pick this stuff up to protect your house, when that's not what it was designed for, and in fact it's not aimed at consumers' home offices at all. This RF shielding material was designed for high security facilities, such as government data centers and big corporations that have lots of valuable data to protect (not naming any credit card companies - you know who you are); places where you don't want anyone with a wireless card or cellphone transmitting data without anyone being the wiser.
The article also has a comment from Bruce Schneier about properly securing your wireless infrastructure being more cost-effective than coating the windows with this stuff, and he's got a point: This Faraday shielding film was horrendously expensive when it was still classified, and it'll take a few years before it comes down enough in price to really be affordable. 802.11b access points only implement WEP, which is at best a stumbling block these days for intruders and not even much of a deterrent. 802.11g is worth the time and money to upgrade to, not just because it's faster, but because WPA is much harder for an intruder to crack; moreso if it's deployed in a corporate environment and is backed with (say) cryptographic certificates.