A brand new application called MultiWriter has just hit the Fedora 21 repositories that allows you to write a single ISO (eg. the Fedora Workstation Live Image) to multiple USB drives all at the same time. The application is super simple to use, just insert the USB storage devices you want to write to make show up in the MultiWriter interface, then press a single button to choose the ISO and MultiWriter will image the ISO to all those USB drives.
This little app is awesome for people that need to create many USB versions of Fedora for giving to others. Multiwriter can image the ISO to up to 20 USB drives at once, and works well with USB hubs (unless your computer already has 20 USB ports for some reason)
Multiwriter is now available in the Fedora 21 repositories, so you can install it using the Software application in Fedora Workstation, or on the command line with:
sudo yum install gnome-multi-writer