Bruce Schneier, CTO, Counterpane Internet Security

"The Coming Third Wave of Internet Attacks: The first wave of attacks targeted the physical electronics. The second wave - syntactic attacks - targets the network's operating logic. The coming third wave of attacks - semantic attacks - will target data and it's meaning. This includes fake press releases, false rumors, manipulated databases. The most severe semantic attacks will be against automatic systems, such as intelligent agents, remote-control devices, etc., that rigidly accept input and have limited ability to evaluate. Semantic attacks are much harder to defend against because they target meaning rather than software flaws. They play on security flaws in people, not in systems. Always remember: amateurs hack systems, professionals hack people."

If this doesn't scare you, nothing will.
He's almost certainly correct.