Earlier this year Creative Commons formally introduced a license waiver called CC0 (CC Zero). I urge musicians, as strongly as I can, to consider using this license waiver for the audio samples they put into the Commons.
Audio samples licensed with CC0 with a CC0 waiver are the most flexible and least restrictive. Put another way, they carry the most freedom. Isn’t it hard enough to be creative?
No matter how highly I consider my musical work on my best days, I would like to think there is balance between my personal desires and choking off my great granchildren’s freedoms to speak creatively.
I've been putting most of my own recordings into the public domain lately, but mainly because it's the only license certain to be compatible with anything that somebody might want to remix with. Also, there's an issue of license obsolescence that I worry about. All I care about is being heard.
Victor's point about freedom is compelling too, though. That's kind of a revelation to me. I remember Gordon Mohr of Internet Archive and Bitzi saying something similar 7-8 years ago, and I wasn't ready to get it. Gordon, you were right.
Also, there's an issue with music that's different from code: musicians just don't understand copyright in any way. Burdening them with the difference between the different flavors of CC license is a non-starter.