I wrote up some background to licensing, waivers, the public domain and how it applies to linked data. I also included examples of how you can declare a public domain waiver for a linked dataset.
http://blogs.talis.com/nodalities/2009/07/linked-data-public-domain.php Hope this helps people with these complex issues. In other news, our tutorial "Legal and Social Frameworks for Sharing Data on the Web" which covers these kinds of issues was accepted for ISWC2009. I am not a lawyer, but we will have an expert lawyer taking part in that tutorial (see http://www.jordanhatcher.com/ ) Ian
