Searches and seizure is not limited to personal computers or laptops. Any device that stores data is fair game for Customs and Border Protection or Immigration and Customs Enforcement (ICE) Agents. This includes all computers, laptops, tablets, mp3 and mobile media players, digital cameras, hard-drives, and any other mobile device you can imagine. If it stores data, Customs can search it. To be fair, the government only conducts these types of searches 300 or so times a month. So the likelihood of being searched is still small.
(Images via bertconcept, grahamstanley and mwichary‘s Flickr photostreams)