The Washington Post says

Federal agents may take a traveler’s laptop computer or other electronic device to an off-site location for an unspecified period of time without any suspicion of wrongdoing, as part of border search policies the Department of Homeland Security recently disclosed.

Fishbowl says

It’s a very timely move by the DHS. You never know when someone might invent a global, unregulated data network that could allow evildoers to entirely bypass such checkpoints, making them nothing more than a sham way for border police to rake through people’s private data and copy their mp3 collections.