They've been doing it for awhile now, but the feds have publically announced they can search any laptop or media device at the border. This is bunk for djs who want to travel to and from the U.S. Make sure your software is legit, kids!
http://www.dailymail.co.uk/news/worldnews/article-1040812/Airport-threat-laptop-U-S-gets-power-seize-iPods-mobiles-new-anti-terror-measure.html
