At Microsoft, the company measures the relevance of what it does by how it maps to revenue, said Bill Hilf, Microsoft general manager of technical platform strategy. He is responsible for the open source strategy at the world's largest software company.

Microsoft is Technologies to promote deployments of PHP applications on Microsoft's Windows Server platform. Open source does not necessarily mean less vendor reliance, Hilf said.

Panelists also touched on the actual subject listed for the session: software stacks. This sparked some sharp disagreements over how easy it is to switch software platforms.

The LAMP (Linux Apache MySQL Perl/PHP/Python) stack, said panelist Marten Mickos, CEO of MySQL, provides a heterogeneous platform that evolves on its own. Bray added that the LAMP stack is pretty swappable.

"From the business point of view, the most important freedom is the freedom to leave," which LAMP provides, Bray said.