Capistrano is a developer tool for deploying web applications. It is typically installed on a workstation, and used to deploy code from your source code management (SCM) to one, or more servers.
"The observer pattern (aka. Dependents, publish/subscribe) is a software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods."
This makes replicated computation as easily as replicating data - and makes synchronization of all events across multiple peers a fundamental property of the system.
Open Cobalt is a free and open source software platform for constructing, accessing, and sharing virtual world both on local area networks or across the Internet, without any requirement for centralized servers.