Umm, this is interesting..

[setuid]

On Sun, 2008-01-27 at 10:10 -0500, Thomas Charron wrote:
> I have never heard of a developer attempting to revoke the GPL on all
> versions past and present before.

Well, first and foremost, he can't. Once the software is released under
the GPL, it cannot be revoked. He can TRY to claim that, but it won't
hold up under copyright law. 

Secondly, it appears as though he's doing it to cover his OWN ass, not
because he's "taking his sandbox and going home". This is reinforced by
the paragraphs near the end, where it states "...it is in your best
interest to remove the software from your system(s) and destroy all
copies in your possession."

It may be that he's trying to protect anyone that uses it, because he
himself may have put code he wasn't allowed to use, into a project which
he then GPL'd to the public.

But he is responsible for the copyright violation, if any such violation
exists, not third-parties who happen to use that same codebase. 

It'll be funny to watch this one play out, but you can't unring the bell
to revoke a license to something already released like that.