Earlier this week security researchers presented their paper highlighting how a man-in-the-middle attack could let Apple, or an agency compelling Apple, read our iMessage despite the end-to-end encryption. Not so says Apple spokesperson Trudy Muller. AllThingsD:
iMessage is not architected to allow Apple to read messages. The research discussed theoretical vulnerabilities that would require Apple to re-engineer the iMessage system to exploit it, and Apple has no plans or intentions to do so.
Beyond that, it's simply not in Apple's best interests to be able to read, or to be able to enable any agency to read, our iMessages. It would hurt them not only as a company, but as a group of people dedicated to making great products.
My guess is - and I say this as someone who trusts no one and is paranoid of everybody - if there's a way to make even this theoretical attack impossible, Apple will find it.