If I'm to be totally honest, I'm probably addicted to the Internet to some degree. I can (and do) step away from it at any time if the need arises, but I'll be right back before long, and I get anxious if I haven't been on for a while (by which I mean days). I end up forgetting to eat and stay up all night checking forums and chatting on IRC.
That said, I think there's some confusion over what it is that people are addicted to. I know people who base their entire lives around MySpace, but that's far from what I'd call "the Internet". For other people it's Facebook or a forum, or something else.
And I think it's probably less serious and widespread than you might think. I keep seeing articles about Internet addiction. I recall one that gave a list of signs to look for. It was so broad, practically anybody who uses a computer enough to know how would fit it, and so ridiculous as to be meaningless. For example, one such sign was making typing motions with your fingers while not at the computer.
_________________
"If knowledge can create problems, it is not through ignorance that we can solve them." - Isaac Asimov