Sergey Brin and Steve Horowitz discuss the availability of the SDK, that it will be open source in the future, and demo applications on the Android platform.
Google Shows Off 'L', Android One
Google shows L, the latest flavor of Android
Android Wear at Google I/O 2014
Google's Android L - What we love and hate
Android L hands-on | Google I/O 2014
How Google designed Android L
Google's Android TV hands-on | Google I/O 2014