Daring Fireball on iMessage encryption (and privacy in general)
John Gruber put this together late last year, and I’ve had it queued for posting since then. It remains a helpful summary of Apple’s approach to privacy, especially as it applies to delivering iMessages between devices.
Assurances from corporations aren’t always very, um, assuring, but so far it seems Apple are leaders in respecting the privacy of their users (even if it’s just to minimise their exposure to subpoenas and such).