It wasn't a public highlight of WWDC, but I learned here that Apple has elected to open the source for the x86 Darwin kernel and created an official project to maintain it and act as a liaison between Apple and the developers working on, and learning from OS X Tiger's system-level source code.
I can say with absolute certainty that I had zero influence on Apple's decision; the decision predates my involvement with the issue. Not many truly understood why I made this my hill to die on, so fewer still will understand why I'm so elated at this news. Far from being icing on the cake, Apple's direct engagement with open source developers, and high-end users who need to tune and alter their systems for peak performance, will dramatically alter the landscape. With the community's involvement, Apple will set a standard for openness that will show other first-tier OS vendors' open source efforts as lip service to the letter of a license. Apple has opened many technologies, including Bonjour, Open Directory and launchd, that others would unquestionably hold as proprietary to maintain a competitive advantage.
To Apple management who wrestled with the balance between public engagement and the protection of IP, and to the Apple developers who busted hump so that Apple could roll this program out at WWDC, my heartfelt thanks. This will be remembered as one of Apple's smartest strategic decisions.