Unlicense Yourself: Set Your Code Free

> How often have you passed up on utilizing and contributing to a great software library just because its open source license was not compatible with your own preferred flavor of open source?

Famously, Sun's implementation of ZFS isn't allowed in the Linux kernel since the CDDL isn't GPL-compatible. But aside from that, are there any other real-world cases of license incompatibilities between two FOSS projects that people would have otherwise combined?

> In order to ensure your project remains completely free and unencumbered by anyone's copyright monopoly

This only works for code contributed back to your repository. Normally, you'd expect phrases like that to refer to forks too, which is what copyleft gives you.