I enabled the Twitter Login extension, added my API key and Secret then while trying to log in with Twitter recieved this in the popup window:
Received HTTP status code [401] with message "<?xml version="1.0" encoding="UTF-8"?> <hash> <error>Desktop applications only support the oauth_callback value 'oob'</error> <request>/oauth/request_token</request> </hash> " when getting temporary credentials.