NREL has released their open source databus. They spin it as energy data (and a system for campus energy/building energy) but it is very general right now and probably will stay pretty general. More information can be found here
http://www.nrel.gov/analysis/databus/ The source code can be found here https://github.com/deanhiller/databus Star the project if you like the idea. NREL just did a big press release and is developing a community around the project. It is in it's early stages but there are users using it and I am helping HP set an instance up this month. If you want to become a committer on the project, let me know as well. Later, Dean