Seen this? Police Tape
http://dvice.com/archives/2012/07/aclu-app-secret.php
That's where the ACLU of New Jersey's new Police Tape "police accountability app" comes in. It will allow users to record audio or video from their smartphone while the screen remains dark, appearing to be off. The footage can then be automatically uploaded the the ACLU-NJ's servers, so it can't be erased by police.