ArsTechnica just posted an article on how to create a USB Install drive.
Basically, format an 8gig or higher USB drive, name it Untitled and run the following script
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
Basically, format an 8gig or higher USB drive, name it Untitled and run the following script
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction