KOffice has an extension for supporting RDF in its ODF format. As all is XML, this is an excellent way to go. Read Ben Martin’s post about it.
http://monkeyiq.blogspot.com/2010/01/koffice-and-rdf-say-it-with-style.html
Some excerpts:
The ODF document format lets you store RDF/XML data inside the document file, which in turn lets both a human reader and a computer know about things that comprise an office document. You can refer to a person, place, or time and have the computer know what you are saying without having to resort to heuristics.
Of course, you can drag and drop items from the RDF docker into kaddressbook and korganizer. These pieces of information should be able to be moved into and out of an ODF file using KOffice without thinking about it. You want to add Fred to the text, pick him up from your kaddressbook and drop him into the RDF docker. Your default contact stylesheet is then used to insert some text into the document at the current cursor location showing you the Fred contact. Quick and simple… Lets make RDF something everybody uses but nobody needs to learn about (unless they want to).
It also features a (silent) video:
KOffice and RDF: Say it with Style… from Ben Martin on Vimeo.