In 2011, we made 10 881 enhancements/changes to Firefox, together with 83 new features and 135 new APIs. Firefox introduced Do Not Track to the industry, something that was quickly followed by others. Firefox Sync is being used by a lot of people, and in 2011 there were 25 billion items synced. Firefox for Android has some exciting features lined up, available for testing in the Firefox Aurora and Firefox Nightly channels. Firefox has a number of exciting features in store: Web Sockets and WebRTC support for real time audio and data communication.”]
Source: https://hacks.mozilla.org/2012/03/firefox-in-2011-firefox-plans-for-2012/