Even though the title says "laptop", the article explicitly mentions that this applies to any electronic device (cell phone, USB stick, camera, etc). This is especially important in light of point #3 below.
http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9062299
Please read the article for more details, some of which are quite chilling if you were naive enough to expect anything better. Oh and this applies to US citizens also. And it applies even when you are leaving the US :-)
Best quote:
If it's information you don't want to share, don't carry it. That includes data such as personal banking information, photos, correspondence, health and password information. If the device is a company-owned computer, don't carry proprietary business information or personnel records on it, the ACTE advised.
Some other quotes:
"But we think people should know that they basically are leaving their right to privacy at the door when they cross the U.S. border. There is no assumption of privacy," at a port of entry, she said. Here are five factors Gurley says travelers should know about:
1. No evidence needed to take your laptop
2. Anything can be searched
3. Your PC might not be returned right away
4. Don't take anything you don't want to share
5. Be cooperative
"Our primary concern is to alert travelers that their laptops and other electronic devices can be seized at a border without explanation, provocation or even likely cause," she said