Yahoo Scanned Everyone's E-mails for the NSA
Other companies have been quick to deny that they did the same thing, but I generally don’t believe those carefully worded statements about what they have and haven’t done. We do know that the NSA uses bribery, coercion, threat, legal compulsion, and outright theft to get what they want. We just don’t know which one they use in which case.
EDITED TO ADD (10/17): A related story.