If you have a child under 18, the answer almost certainly is yes from a legal standpoint.
Okay, let me back up for a minute. Longtime readers know that I am an NPR junkie. I was listening to the NPR show On the Media today. They covered the recent Lori Drew trial. Lori Drew is better known at the Myspace Mom who created a fake profile, communicated with a 13 year old girl, sent a nasty break up message leading the girl to commit suicide. Drew was recently convicted of three counts...of illegally accessing a computer...i.e. hacking. The prosecution's case rested on the fact that she violated Myspace's terms of service, therefore, she "hacked" the system.
How many people read terms of service? Google's terms of service state that you may not use the service if you are not of legal age to enter into a contract (18 in most states....see section 2.3). So if you want to play it safe, better keep your kids from using Google and we had better block it from schools since almost all students (save some seniors) are under 18.
Just for giggles, I decided to check out the JT's terms of service. Go ahead and read them to see how well they are enforced. Oh, and did you know that they claim intellectual property rights over everything posted there? They also prohibit reposting of copyrighted works (also known as the great cut and paste of articles) and you also may not "Use the Site to upload, post, email, transmit or otherwise make available content that is harmful to minors in any way, or that is harassing, harmful , threatening, abusive, vulgar, obscene, defamatory, libelous, hateful , or racially, ethnically or otherwise objectionable. "
In other words, a zealous prosecutor could have a field day going into those forums and charging people left and right with hacking! This strategy is becoming more common and could very easily be abused. I could put all kinds of ridiculous items in terms of service and then go after anyone I didn't like who violated them!
This is not a defense of Lori Drew at all...but I bet the legal theory she was convicted with could be used against virtually ANY internet user on the planet.