After few delays, Fedora team finally announced that the new Fedora 21 will be available on December 9, 2014. The leader of Fedora project, Matthew Miller, stated “We are now in the ‘Final Freeze’ for Fedora, the last polishing period before the release. This means that packages updates are only allowed via a special exception process, as we work to deliver a solid, stable release to our users on December 9th”.
So, be patient and wait until the day to get the Fedora 21 Final Release. Before that, you may download the Fedora 21 development version.
