If you take the Unicorn.SharedSecret.config.example file and rename it to .config, it will explode because it loads before the UI config file (http://sitecore.stackexchange.com/questions/1015/unable-to-cast-object-of-type-system-string-to-type-unicorn-controlpanel-secu/1024#1024).
This will be fixed in the next version of Unicorn by renaming the file to Unicorn.zSharedSecret.config.example and adding a note on load order to it.