[jarfil]

> when you license something under BSD, at any point you have the power to take it to another license or make it proprietary

And that's why I would NEVER contribute code to any of your projects. You want people to work for you for free, then when you're ready just close the code and run with it? Yeah, right, try again.

The GPL is a "you can't screw me, I can't screw you" license. The BSD is a "whatever" license, much like the MIT or a CC0/Public Domain. If I don't care about the code, if it took me no effort to create, I may consider the BSD... or just the CC0, whatever. Otherwise, you're either looking at a real contract or the GPL, and you better don't try to screw me either way.

Oh, and you can re-license YOUR code under any license you wish. If you published it once under the GPL, it only affects whoever may get it from that publication; you can still re-publish it in the future under any other license you wish, since it's YOUR code, to do as you please.

[antihero]

If it's GPL'd, what prevents the author/project owner simply changing the license though?

[bzbarsky]

Nothing, if they have copyright on all the code.

If they accepted changes from someone else, that someone else has copyright on those changes and the license can't be changed without them agreeing to it (or possibly their changes being removed from the codebase; I am not an IP lawyer and you should consult one if you want to be sure on this score).