The Electronic Frontier Foundation is reporting that a US Federal District Court judge in San Francisco has ruled that National Security Letters are unconstitutional as a violation of the First Amendment of the US Constitution and the separation of powers. The Judge's order has been stayed for 90 days to permit the federal government time to appeal.
National Security Letters (NSLs) are a form of administrative subpoena that can be issued by a senior official of the FBI, which requires the recipient to provide non-content or transactional information and is usually accompanied by a gag order.
According to EFF's media release, Judge Susan Illston ordered that the FBI stop issuing NSLs and cease enforcing the gag provision in this or any other case.
A copy of the Judge's decision is available here, also on the EFF website.