ReadWriteWeb points readers to a report released by the 451 Group stating that open source is not a true business model, but more of a business tactic.
Traditionally, the open source business model is perceived as free/open software, with paid support and configuration services. The report found, however, that many of the responding open source businesses incorporate some commercially licensed software in their product line. It also found that the paid support/free software idea -- while theoretically, at least, valid -- is multi-layered, complex, and highly variable between software product, software company, and industry.