Open source FaceTime was a claim never materialised and now sits in stark contrast to Swift. Apple has exceeded expectations with the public Swift, posting full source code for the compiler and standard library, an Objective-C independent interpretation of the Foundation framework, libdispatch for Linux all accompanied by extensive documentation and a full commit history of the repo dating back to the first push from Lattner in July, 2010.
Perhaps even more out of character, the Swift documentation includes for both rejected proposals and future planned changes to the Swift language. You can read about language changes that were being explored, tentative usage examples and reasons why the components were scrapped. Apple has tipped the hat on significant language changes that would in any other year be secret until WWDC 2016. Going forward, upcoming potential changes will be added and likely discussed with the community, giving developers intimate access to the project’s evolution. This is a monumental outlier, in a good way, when compared to the rest of Apple’s framework engineering.