A BarCamp (explanation) around open data, with the motto 'all you ever wanted to do with open government data, but never dared to ask' Held in Paris, December 12th 2009. More info in French

There are three themes on the agenda:
1) sharing of experiences with opening up data in France, EU and USA
2) creating innovations/services/apps based on open government data
3) discussion of societal impact of open government data (justice, sociology, economy etc.)

The event is hosted by several organisations and seems well sponsored.