Listening to the signals that end up on your property probably couldn't be made illegal, provided the signals were unencrypted. On the other hand, accessing someone else's network (ie, sending data or queries into that network and/or using services it provides, such as internet access or access to other computers on the network) is pretty clearly illegal.
but hey by some peoples logic if you forgot to lock your door i could wonder in and use your loo .
HOWEVER, this is totally irrelevant, because my first post was about using the N8x0 to play on a computer, a la Maplestory, Grenda Espada, etc...