By Nelson King (Intelligent Enterprise)
"Commercial open-source software" certainly sounds like a contradiction in terms. The phrase "free and open" is part of the definition of open source software, which translated into real terms means that people can download the software and source code at will and for no charge. In most instances, this is how open-source works. Where it may work less well is for the enterprise.
Here's what Bill Hilf, Microsoft's General Manager of Windows Server Marketing and Platform Strategy has to say in a recent Information Week interview: "When people buy commercial software, really what they are buying is a guarantee. You're buying a guarantee that what you have will perform, and has been tested and there's someone you can call up, and if things go really bad someone's liable if something doesn't work. You're buying this ecosystem of accountability."

http://www.intelligententerprise.com/blog/archives/2007/12/isnt_commercial.html