Well grondilu pointed out the linux kernel. That's not exactly "small, niche and useless to a vast portion of the community that would use it".
Irrelevant example, comparing apples and oranges. The Linux kernel is not a library.
Applications do not link directly with the Linux kernel, therefore applications (obviously!) may be any license.
I'm must say I'm quite surprised by this GPL hate.
Where is the hate, in my message? I am simply stating facts. Linux kernel developers have been deeply involved in the arcane legal issues of licenses and linking for well over a decade.
And even excluding my kernel work, you will see that many of my projects are GPL license:
https://github.com/jgarzik (basically all the non-python projects are GPL'd)
The Linux kernel example is simply not applicable to the cbitcoin licensing situation, because it is not a library against which people directly link their end user applications.
The facts are:
1) If cbitcoin is LGPL, an application using cbitcoin may be any license.
2) If cbitcoin is GPL, an application using cbitcoin must be GPL.
3) Linux kernel is not a library against which user applications directly link. The kernel is GPL, but applications using the kernel's system call interface may be any license.
