Selling commercial rights to work already released under a Creative Commons license

My friend Cory Doctorow (one of the more interesting of the current crop of Science Fiction writers, though he may be more well-known from his work with the EFF and his role with the award-winning blog boing boing) has posted a very interesting piece about how one can commercially exploit CC-licensed content:

Lots of people have asked me whether doing a non-commercial CC release makes it impossible to sell commercial rights to a traditional publisher. Here’s how it can work:

The exclusive rights granted to Licensee hereunder are subject to a pre-existing Creative Commons license which grants members of the public the irrevocable and nonexclusive right to create their own adaptations of the Licensed Property, including comic books. Such Creative Commons-licensed works may not be sold or distributed for profit. Licensee acknowledges that under the terms of this Creative Commons license, members of the public may create comic book version of the Licensed Property for non-commercial distribution. Licensor agrees not to license the rights which are granted to Licensee hereunder to any competitor of Licensee or to any commercial enterprise intending to create adaptations of the Works for commercial distribution.