I may be a bit previous in talking about licensing models when a distributable module has yet to exist but, having just been reading up on licensing issues, would like to clarify the positions of this and the companion DCMetaSpider project.
Whilst I find the GPL rather confusing and scary (not that I am saying that it is not good), Drupal itself is distributed under the GPL and my interpretation of that license is that all modules should also be distributed under it. So, Dublin Core for Drupal will be GPL'd.
I am under less constraint with the DCMetaSpider project and will eventually release it under the terms of a much simpler, IANAL-friendly Creative Commons license.