Hi Bill,
I'm sure someone will correct me if I'm wrong but, I believe that technically any device that allows it's config to be downloaded over SSH or Telnet is supported. Out of the box, there are a variety of device templates included to allow automatic config downloads. If you find that a device you'd like to download a config from isn't included in the templates, you can search Thwack for user created ones or make a custom one based on the commands you would normally enter on the device to display/download the config.