For Fedora users, just keep calm and use Fedora 20 for now. Fedora Developers has announced that Fedora 21 official release date is now 14th October, 2014.
Fedora 21 which has been slated for August has been rescheduled for October. This is because shipping in August will leave Fedora 21 between GNOME 3.12 and 3.14. GNOME 3.14 which will be released by late September hence shipping new Fedora mid or late October will allow for a GNOME 3.14 desktop in Fedora 21.