Is using other' ppl wireless network considered a crime?

Yes. Technically that's a crime, and there have been plenty of cases of prosecution resulting from it.

Although personally I think it's fair punishment if you're stupid enough to leave your network unsecured. That argument won't work with the cops though- if someone leaves their front door open doesn't mean it's legal to burgle them.

Yes! is a crime if you get caught. So, behave yourself when you are in the net. Do you know, in Singapore if you post some sensitive articles in the net, you can easily get caught, not like other countries. Singapore is too small, therefore you have do behave yourself in any other things beside serving the net. Totally not a place to practise illegal things here.

A wireless network transmits over a certain amount of distance. If it is left unsecured, and accessible from your property or privat property, then no it is not a crime to use it. It becomes a crime when you use it to access their network and computers or have to go onto their property to get a signal.

no, if they are so stupid as to not lock the site, you can use it. They are the stupid ones...they open the door to complete analysis of there drives, copying data, useful in identity thefts. The same people will probably have a word document with all their passwords on it...for banking,etc. Talk about stupid.