In a country where citizens are proud that the rule of law says we are innocent until proven guilty, it is unusual that the US is now able to seize electronics at border crossings — even from US citizens — without probable cause. The items seized can be held indefinitely and if there is nothing deemed a security risk on the devices, any backup copies must be erased by the government.
This applies to all devices such as laptops, cell phones, iPods, etc.
Here is the actual government document describing the policy.