If the latest round of statistics are to be believed, the GPL -- the most popular license for open source software -- is undergoing a slow but fundamental shift. But if the same statistics are to be further believed, other licenses are also gaining ground on the GPL.
The stats in question are part of an ongoing effort by our old friends Black Duck Software, who harvest and tabulate licensing information about open source projects and then publish the resulting data. In the last year, two changes have taken place that are worth mentioning:
I am willing to bet these changes are part of two trends at work. #1 is part of the growing awareness amongst the little guys that the major software movers and shakers are getting more into open source -- using more of it, writing more of it, providing more of it -- and using GPLv3 is a good way to protect their work from being re-used in a manner that benefits only the big guys.
#2 seems reflective of the growing diversity of people, big and small, writing open source. That much bigger a crowd means that many more approaches -- and it also means growing awareness of what the long-term implications of picking a given license are. I know one programmer who no longer uses the GPL for anything, because he wants to avoid the political implications of the GPL entirely. (He uses the BSD license.) Another fellow I know is a GPL diehard, although not a v3 user. I've used the MIT license for what few pieces I've distributed. Take any four other projects with different licensing, and ask them why they chose the license they did, and you may well get startlingly different answers -- even for the same license.
A while back I wrote that consolidating on the GPL had one advantage: it was widely-used and well-known, and open source as a whole had enough obstacles, so why complicate things further? But that was, in its own way, as limited a view as those who avoided open source entirely. I've come to feel that a diversity of licensing is useful for the sake of allowing software to be developed and distributed in ways that complement both its creators and users -- as long as there are ways to sift through the confusion, too. The OSI "Good Programming Seal of Approval" for licenses helps, but from what I've seen, very little beats word of mouth, face-to-face testimonial about open source at work.
I don't think GPLv3 will become the GPL as we know it, and I don't think the GPL as a whole will be eclipsed entirely, either. But they're not the only game in town, and shouldn't be.
InformationWeek Analytics has published an independent analysis of the current state of open source adoption. Download the report here (registration required).