anything that gives out a wireless signal without the need for a encrytion key is an open node, that can be used by anybody. i use my neighboors all the time with my psp, i have even talked to them and they dont care, its a matter of knowing how to protect yourself. i went wardriving with some freind a couple of weeks ago, and there were people that had open nodes with no protection with their files, and some with protection for their files, but still having an open node. if you leave your acsess point unencrypted without any protection from your files, it shows you have made no attempt to turn people away from using that point, therefor there is no real reason to sue/arrest someone for using it, you havent made an attempt to keep people from using it. if you have and people still use it, then you can sue/arrest for it. so if you dont want someon leeching your wifi, encrypt it, if you dont care and like the idea of public domian, then leave your acsess point open, and protect your files.
my 2 cents.