I see copyleft as a kind of parody on copyright. The name itself is a play on words. Its goal, respecting freedom, is an admirable one. Copyright's goal on the other hand is not very admirable. Copyright exists to enforce an artificial monopoly on ideas, the primary incentive of which is to protect the financial interests of creators. The impetus behind copyright is not all bad--after all, the laborer is worthy of his wages. But it has the nasty side effect of making creators over-protective of their work. If creators were fairly compensated for the value they provide they might not feel such a need for copyright protection. That's why I hope things like gittip and Kickstarter become more and more mainstream.

Copylefting a project says to the world that we value freedom more than compensation. It's the right message but depends on the wrong "logic" of copyright. Ideally, we would all reward companies that value freedom above profits, thus ensuring that freedom is profitable. But for now, copyleft exists as a strong-arm tactic against the over-protection of information. In the sense that copyleft utilizes copyright law to enforce freedom, it's hard to say whether GPL or other open source licenses have a greater respect for freedom.

>...unless it led to a world of rented locked down single-purpose appliances run on gifted code...

There would have to be some other enforcement mechanism to prevent this for Stallman to be happy. He may not think that's possible, but I'm sure he would be happy to be proved wrong.

I think that a post-copyright regime could easily require code exposure for computers that are sold to consumers - that's far less radical than a post-copyright world would have already been in order to abolish the stuff.

Ironically it might be in the form of a EULA or developer agreement.