The plugin parses addons_config.mk and will use it to tell which system frameworks to add, which folders to ignore, extra includes to add, etc. Example folders are always ignored by default. It will also use some of the meta data, such as the dependency list and addon url. If your addon doesn't work with OFPlugin properly out-of-the-box, you should add an addon_config.mk. See ofxKinect and ofxMidi for examples.
Download here : http://adamcarlucci.com/ofplugin.zip
Copy plugin in /Library/Application Support/Developer/Shared/Xcode/Plug-ins/