Taking their lead from jessamyn, Apple has included a warrant canary in their transparency report.
"Apple has never received an order under Section 215 of the USA Patriot Act. We would expect to challenge such an order if served on us."jessamyn created the warrant canary in response to the USA Patriot Act, which permits warrantless searches of library records and prohibits the library from making the existence of these searches known. It does not explicitly prohibit the library from stating that it has not received any secret search warrants. To the best of my knowledge, this is the first use of a warrant canary by a big, high-profile organization. Nice work, jessamyn!