The idea behind the EU-funded Hydra project is to reduce the complexity involved in networking various consumer-oriented devices from different manufacturers. It does so by coming up with a service-oriented middleware. The overall goal, according to researchers at the Fraunhofer Institute for Applied Information Technology, is to more easily build devices that can be networked easily and flexibly via web services.
With Hydra, devices such as electricity meters, TV sets, refrigerators, stereos as well as heating and lighting systems, can be networked without designers of one device having to know what goes on inside other devices with which they are trying to communicate. Researchers at Fraunhofer say they have constructed prototypes and Hydra demonstrators with an ordinary Playstation 3 serving as a home control center.
The middleware provides a standard interface so software developers needn't think about what kinds of sensors are in a given house. To get a value for temperature, as an example, a device would ask the middleware for the information. Hydra would then figure out how to resolve it and provide access to the right sensors to handle the query.
More info from the Hydra program site: http://www.hydramiddleware.eu/news.php