This article at Boing Boing about Marriott’s petition with the FCC to be able to block personal WiFi networks on its properties is also a very informative primer on how these networks work:

Marriott is fighting for its right to block personal or mobile Wi-Fi hotspots—and claims that it’s for our own good.

The hotel chain and some others have a petition before the FCC to amend or clarify the rules that cover interference for unlicensed spectrum bands. They hope to gain the right to use network-management tools to quash Wi-Fi networks on their premises that they don’t approve of. In its view, this is necessary to ensure customer security, and to protect children.

The petition, filed in August and strewn with technical mistakes, has received a number of formally filed comments from large organizations in recent weeks. If Marriott’s petition were to succeed, we’d likely see hotels that charge guests and convention centers that charge exhibitors flipping switches to shut down any Wi-Fi not operated by the venue…

The FCC reserves all rights to the regulation of wireless spectrum to itself. Even licensed owners of spectrum—such as cellular networks—aren’t allowed to employ techniques to jam other users. Rather, they pull in enforcement from the FCC, which tracks down, shuts down, fines, and even proffers criminal charges against violators.

Marriott is asking, therefore, for a unique right: the right to police spectrum privately based on property rights. As Cisco put it in its comment, “Wi-Fi operators may not ‘deputize’ themselves to police the Part 15 radio frequency environment.”…

So far, there’s no organization representing consumers, small businesses, trade-show exhibitors, or business travellers that has submitted a comment, though a couple dozen individuals have. The affected parties are these groups. The original complaint against Marriott came from a savvy business traveller who saw what was up. Should Marriott get what it wants, we’d all have to use hotel or convention Wi-Fi; portable hotspots would fail, and our cell phones’ Wi-Fi sharing would be disabled, though USB and Bluetooth tethering would continue to work.

There’s also no representation from businesses and people adjacent to hospitality operations. If a hotel is in a city, how can it possibly protect just its own network without disabling all the dozens of networks around it without whitelisting those networks—in effect, requiring neighbors to register with them.

I’ve been involved in managing and organizing trade shows and conferences for multiple organizations and I can tell you from personal experience that the hotels and convention centers charge incredibly high rates for often spotty internet connectivity for exhibitors and guests. I’ll be interested to see if one of the organizations I belong to, the ASAE, comes out against this. Its members are people who work for associations, many of which spend a significant amount of their time and budget on trade shows and whose own members would be subject of these “jamming” techniques.