Talk about burying the bombshell. From the Swift Mailing List:
I'm happy to announce that Ted Kremenek will be taking over for me as "Project Lead" for the Swift project, managing the administrative and leadership responsibility for Swift.org. This recognizes the incredible effort he has already been putting into the project, and reflects a decision I've made to leave Apple later this month to pursue an opportunity in another space. This decision wasn't made lightly, and I want you all to know that I'm still completely committed to Swift. I plan to remain an active member of the Swift Core Team, as well as a contributor to the swift-evolution mailing list.
Lattner is one of the most influential and important figures in the history of modern developer tools, responsible for LLVM, Swift, and many of the systems use by Apple and Apple's community to create apps.
It's great he plans to continue on with Swift, which he ran at Apple, but it's less than great (for Apple) that he plans to do it from the outside.
Thanks to Chris Lattner for everything he's contributed and best wishes for whatever he takes on next. There's approaching zero chance we've heard the last from him.