Apparently, laptops may be legally seized and searched at U.S. borders, they may even be kept and not returned.

“My laptop was initially searched by one person, but he called for backup” when he saw the blueprints. “It seemed they were convinced I was sent to plant bombs in those nonexistent buildings.” He said he hasn’t seen the laptop since.

It probably happens very rarely, perhaps randomly (although there was the case of someone who had his laptop searched because there was a report of child pornography or similar on him).

One more reason to avoid going to the U.S., I guess. Not a decisive reason, my family and I aren't going to the U.S. until at least after George W Bush is out of office, and probably not even then, unless the TSA and the Department of Homeland Security have either been dismantled or become accountable for what they do. As it is, I'm not risking my laptop in checked luggage (although possibly that restriction is lifted now) and I'm not risking losing it and never getting it back just because it's impossible to get anything out of TSA or Homeland Security (since the judiciary and police will bend over backwards even if there is no case).

There's no important information on my laptop (all my mail is on gmail, and the CIA already has all of my mail, and even if they don't, the NSA does), but I'm not some rich american who can afford to buy a laptop every month. So I'm just not going where they can take my laptop and never return it (and because I've been so critical of George W Bush's incompetent administration, I'm not going to be a random sample, they'll do it on purpose).