Taking your laptop into the US? Be sure to hide all your data first
guardian.co.uk
guardian.co.uk
The fact that you can just send any incriminating data over the internet instead of carrying it into the country on a laptop/HDD/etc. shows how pointless these searches are. Did I say pointless? Violating.
So basically the only people who get screwed by this are the people who haven't actually done anything wrong but forgot to delete any sensitive/embarrassing content from their drives. The criminals will just use a normal internet connection. Just as with everything else these days: violate the privacy of innocent people as much as possible so they won't notice that they're incapable or too lazy to do any real law enforcement.
http://www.schneier.com/crypto-gram-0805.html#3
As usual, Bruce Schneier has solid advice.