MV3D is an open source virtual world simulation framework written in Python. It was designed with scalability in mind and aims to be able to distribute a world across as many servers as needed while dynamically balancing the load.
Powow is an open-source TCP packets exchange mesh. It allows many TCP clients to connect to a "Powow cloud" (several instances of Powow), to exchange data. Powow is a TCP socket server like Palabre or Oregano.