Details are beginning to emerge about Sun's license for Solaris, presumed to be the Common Development and Distribution License (CDDL) that is being discussed on the OSI list. As many expected, the license will likely be incompatible with the GNU General Public License (GPL):
Like the MPL, the CDDL is not expected to be compatible with the GPL, since it contains requirements that are not in the GPL (for example, the "patent peace" provision in section 6). Thus, it is likely that files released under the CDDL will not be able to be combined with files released under the GPL to create a larger program.
This doesn't come as a surprise. Sun wasn't expected to provide a license that would allow intermingling with GPL'ed code, nor was it likely that Sun would pick the GPL for its Solaris 10 release. So, we have yet another open source license for developers to mull over. Though I'm disappointed that Sun chose to go with a brand-new and GPL-incompatible license, there's nothing I find objectionable about the CDDL itself. It would also be interesting if the next version of the GPL now being worked on happened to be compatible with Sun's CDDL...
As David Wheeler points out, GPL-incompatible licenses don't do well when it comes to gaining support from open source developers. For example, the Mozilla Project relicensed due to concerns that the Mozilla Public License (MPL) wasn't compatible with the GPL and to encourage developers to use and work on the Mozilla codebase.
Sun may prove to be the exception to the rule. Solaris has a passionate following, and Sun isn't waiting around for open source developers to move the ball forward they're simply hoping to take a page out of Linux's playbook and give customers another reason to choose Solaris over Linux. Will the licensing change make any difference, or slow adoption of Linux?