At present, more and more commercial firms are getting involved, to various extents, in the Open Source (OS) movement. While several studies have examined incentives and business models of these OS-based software companies, very few works have investigated whether and how firms actively participate to open projects. This paper contributes to the literature by providing empirical evidence on the role and the activities of software houses in community developed projects. The research proposes an original methodology of large-scale primary data collection from OS project repositories and linked web sites. The findings show how different today?s OS movement is from its origins and how important firm involvement has become.