In Milwaukee you still see a lot of open access point, some still have the default name of the router broadcasted. Their well meaning techie friends may have warned them about the horrors of open Wi-fi, which includes being held libel for anything done on your network. It appears that a court will soon rule on whether or not that's the case.
Techdirt reports that the EFF has filed a brief arguing that having an open Wi-Fi network isn't negligence, and the provider cannot be held responsible for the action of others. The case has to do with a porn company that filed a copyright infringement case against a crowd of defendants. Most of these were settled, including many who simply had open networks. The porn company's lawyers convinced them that this was a form of negligence. This is the crux of the EFF's amicus brief, arguing that this is in no way a form of negligence. There is some wiggle room that some of the users may have known others were using their network, and they allowed them to continue. This still shouldn't qualify as negligence.
This could be a case that can help put an end to these sort of lawsuits. Copyright holders have been trying to run dragnets to round up revenue, and often pushing people to settle when they weren't responsible for anything. Go over to Techdirt to read the entire brief.