While it's not specifically PHP-related, it is interesting to see a new tred when it comes to the use of RSS feeds, and this new post from the Circle.ch weblog talks about some things del.icio.us is doing.

del.icio.us is currently experimenting with RSS feed licensing. This is an important issue. Information in an RSS feed should be licensed as one does with the blog posts too. What, if one does not want to have others to use his content commercially? The licensing is there to talk about it. Make a clear statement now and make the users clear, what they are allowed to do with your feed and eventually what they must not.

If you choose a Creative Commons license be aware, that they are non-revocable, so consider thoroughly. I have chosen an attribution sharealike license though for my del.icio.us feed. What the del.icio.us license selector for CC licenses IMHO currently is missing of, is a per-jurisdiction selection.

I'm not exactly sure what the point of licensing the feed really is - it's not like you own the links inside it (well, you could I guess). One could argue that its a creation of your own, a gathering of information that you made, thus a sort of "original work" - but why would you need to protect it?

Even on this site, where there are bits from other articles and a little commentary from myself, I can't really see the advantages...