Flying into the US from "certain overseas airports" could prove difficult if your electronic devices are low on power. According to Circa, the Secretary of Homeland Security has directed the TSA to implement enhanced security measures regarding personal electronics. Devices which do not power up will not be allowed on the plane, and could subject the holder of the device to additional screening.
Other reports have indicated those "certain overseas airports" are those from the Middle East and northern Africa, as fears of anti-US action escalate in the area. There has been no mention of domestic flights falling under this same policy, but you still might want to make extra sure you've got enough juice to get through security.