Yes, it's from the Dummy extension. When I click the "Add Server" button on the Servers page, it lets me choose an agent type -- self-hosted, IIS-hosted, SSH-based, or Dummy Agent. I was hoping to use dummy servers as stand-ins for real servers that don't (yet) exist so I could create my deployment plan before the servers exist. Then, once they exist, I would just point the deployment steps to the real servers.