TechDirt [ http://techdirt.com/ ] has an excellent writeup of what you are and aren’t liable for if someone out there is using your wireless network for nefarious purposes, whether it’s your friends that come over and bring their laptops or whether someone’s parking outside of your house and downloading copyrighted or illegal material to their computers using your open wireless access point. Essentially, if you are legally sharing your wifi, you are a service provider, and for that you are NOT liable for what other people do on your wifi. Some people have even left their wifi purposefully open specifically for this reason.
It’s definitely a good blurb, and there’s a lot of good information in the comments section as well, so check that out for more information. I have to admit that you can get around the issue altogether by securing your wifi, but I definitely understand the compelling arguments to leave your wifi open and share your internet access with your neighbors and community. Regardless of what you choose to do, make sure you go into it with both eyes open!
[ TechDirt :: Are You Liable If Someone Does Something Illegal On Your WiFi? ]