One of the unsung features of GPLv3 is its grant of compatibility to the Apache and Eclipse open source licenses. Apache or Eclipse licensed code can now be combined with GPL code without creating a violation of the GPL. That wasn't possible in the past, or at least, not sanctioned by the Free Software Foundation.Both the Apache and Eclipse Foundations sponsored business friendly licenses that allowed open source code created under their terms to be combined with clearly labeled, proprietary code. Their open source code, such as the Apache Web Server or the Eclipse programmers workbench, could and did serve as the foundation for many new commercial products.

But the way they worded the rights and responsibilities of the downstream users differed in degree, if not intent, from GPLv2. And for a while, as GPLv3 went through its successive drafts, it looked as though those differences weren't going to be worked out.

That posed a headache to open source developers starting with GPL code but wanting to incorporate something from the Apache camp. They could do so only at the risk that the Free Software Foundation might decide to take an enforcement action against them for violating the GPLv2's terms. The GPLv3 as it was issued June 29 included "late changes to ensure compatibility with the Apache license-'compatibility' meaning that Apache-licensed works can now, in the views of the authors of the GPLv3, be used inside GPLv3-licensed works," wrote Brian Behlendorf, co-founder of the Apache Software Foundation, in message as he took a break from his travels in Thailand.

"This what Apache has long wanted because we do want them [GPL-oriented developers] to use it [Apache code], and we didn't like even considering the prospect of GPL-only re-implementations of our works just for compatibility's sake."

GLPv3, he added, "is good news, from my perspective."

A user of the Apache license, Rod Johnson, lead developer of the Java framework, Spring, is by temperament a skeptic of the more ideological provisions of GPLv3, such as its stance against "Tivoization."

But he added, in his own comments to Information Week that those reservations do not signal a fundamental disagreement with the Free Software Foundation.

"I respect the integrity and consistency of Richard Stallman and the FSF. I disagree with Stallman on a number of issues, but he has the courage of his convictions and is true to his vision," he wrote in response to a query about GPLv3. And there are many other open source developers who think there differences over GPLv3 are, now that it's in final form, less than they once imagined.