Today I've read some statements on IRC which I know are true but for which I never found necessary to search for more explanations. Perhaps because they were not relevant enough of because I thought I superfically understood the issues.

ZFS on Linux

ZFS will never be usable on Linux because it's license isn't compatible with the GPL

Well, file, but how is CDDL not compatible with the GPL. Many people can probably answer but I'm not the kind that is very interested in the politics and legal side of FOSS.

KernelTrap has a thread which has some developers discussing why ZFS cannot be included in the Linux kernel. There seems to be a lot of informations about how ZFS rox0r in there but I don't really care about that. I know it's probably an awesome filesystem, but it doesn't really matter since I can't use it.

This thread reveals that one of the problem particular to ZFS is that Sun has taken several patent about its technology. This is relevant because someone could still reimplement ZFS from scratch without looking at Sun's code. If the resulting Sun-free code works, it's doubtful that it will be accepted in the kernel because of Sun's patent on ZFS features.

The list of non-free software licenses at gnu.org doesn't tell much.

A high Google hit on the issue, at sun.com, has some pretty graphics that explains exactly the problem. It seems the viral nature of the GPL license comes in conflict with the "un-erasable" nature of the CDDL. That means if you link a piece of code under the GPL license with a piece of code under the CDDL license, the GPL wants that you use the GPL license for the other piece of code while the CDDL says that you cannot relicense code licensed under the CDDL. This is where the incompatibility remains.

OpenGL SGI

We've been told recently by various news websites that OpenGL as changed its license on OpenGL.

It's Linux.com that has the best article about that issue, covering pretty much everything I wanted to know.

In very short, SGI did a Good Thing. They also did it so fast that no Linux distribution, except GNewSense took step to remove the OpenGL distribution from their Free offering.