I will be giving the closing keynote and also giving a presentation about the joys of XML pipelining at XML Open 2004.
I was in Cambridge a while back at the Optimal XML conference where I did the opening keynote. XML Open 2004 will be more of a challenge as I will need to pull together themes of the conference. Necessarily, it will be a more "on-the-fly" gig but all the more interesting for that.
I'm currently noodling for an over-arching theme. My current favorite is:
a)the relationship between syntactic simplicity and expressive power, and
b)the difference between software as a a hider of complexity and software as expressor of ideas.
There are sessions on Web Services, DSDL, Groovy, Python, Topic Maps, RDF, XPath 2.0 and W3C XML Schema which should provide ample raw material.