Android is now open source software and available for download from official website. It is a software platform and operating system for mobile devices. It is based upon Linux kernel and developed by Google and Open Handset Alliance. Today, Google made exciting announcement - they have now released the source code for Android. There's a huge amount of code and content there, so head over to official website to grab all the details.
From the project site:
Android is the first free, open source, and fully customizable mobile platform. Android offers a full stack: an operating system, middleware, and key mobile applications. It also contains a rich set of APIs that allows third-party developers to develop great applications.