Actually it's not a Google product, Google is just the company that decided to pay for it's development and the developers are technically Google employees. The people behind it are actually the Open Handset Alliance. The entire Android OS is completely Open Source through the Android Open Source Project or AOSP, though there is controversy because Google also has their own closed source components and all the device drivers are proprietary software. Though you can get a complete Google free build based on AOSP so I dunno whats up with the Google hate.