Google Gphone - Android - An Open Handset Alliance Project

http://code.google.com/android/
The Open Handset Alliance, a group of more than 30 technology and mobile companies, is developing Android: the first complete, open, and free mobile platform. To help developers get started developing new applications, we're offering an early look at the Android Software Development Kit.

http://code.google.com/android/adc.html
Cool apps that surprise and delight mobile users, built by developers like you, will be a huge part of the Android vision. To support you in your efforts, Google has launched the Android Developer Challenge, which will provide $10 million in awards -- no strings attached -- for great mobile apps built on the Android platform.