I got a great note from Paul Murphy today.
He suggested I take another look at mixed licensing of open and closed source products and mentioned Sun's CDDL, as used in Open Solaris.
I'd like to go Paul one better, and suggest that in the Linux world, licensing is strategy.
I take for my text the latest announcement from Red Hat, revealed last week by our DataPoint blog, that it will release what was the Netscape Directory Server under the GPL as the Fedora Directory Server.
Red Hat paid $25 million for this technology last November. Now it's being given away.
Red Hat is using the GPL to kick rival Novell's eDirectory, and maybe get customers for Sun's Java Directory and Microsoft's Active Directory asking sharp questions. Sounds good, not just for users but for Red Hat as well.
What do I conclude from this? To many companies the various Linux license schemes represent a continuum of interest. What starts as proprietary under a EULA becomes semi-proprietary under the CDDL, freer under something like BSD and completely open under the GPL.
While the GPL is at the top of the public interest tree, it's at the bottom of the private interest one. By using the GPL, by giving away code and hoping amateurs will enhance it, corporations can wash their hands of failed products and still provide competition to hated rivals.
In other words, licensing is strategy.