Extensions with no license
I think the WMF needs to take ownership of anything submitted, and should consider rejecting anything not released that way.
Specifically, anything donated to the WMF should become property of the WMF to release however it chooses. Then, the donator can specify some license they prefer, or inform the WMF that the donation is already infected with a self-propagating license. In the case of license preferences, the WMF can re-release under GPL, BSD, MIT, CC, Public Domain, or all of those, depending on the non-binding wishes of the donator. For things with a self-propagating license, the list of acceptable licenses should be restricted to the ones already widely accepted and understood.
Having license control means the WMF can release according to the maximum public benefit, and it helps to prevent license proliferation. In addition, it allows the WMF to change licenses if some legal issue is imposed that requires it.
I agree with WMF taking ownership of content posted. So by that - could we then just assign GPL to any extensions that don't currently list a license?
I'm not too opposed to GPL licensing, since it's so well understood and widely accepted, but I think it might be better to make it public domain, like we're already doing for Help:Contents documentation that is meant to be planted into every MediaWiki install (if desired). Making unspecified contributions public domain by default:
- Assumes nothing.
- Imposes nothing.
- Can be changed later, if needed.
In short, if a contribution does not come with any specific licensing restrictions, there's no reason impose any. But, with that said, I think just choosing SOMETHING is better than just leaving it an orphan that everyone is afraid to use because it might turn into an intellectual property minefield.