There is new content available for Revit now from USG Design Studio. This text is found on their site:
USG Design Studio is a free service that does not require registration to use. By registering, you will receive updates on this page for latest content additions, enhancements, and upgrades.
They are currently featuring wall and ceiling assemblies that correspond with their products. Look closely at each page for a link to Revit content and/or template files. Since these are system families you'll need to copy/paste them into your projects or use File menu > Transfer Project Standards to get them loaded.