XML is actually quite cool for similar reasons to those outlined by agntdrake. Here at the company, we needed to re-engineer our infrastructure to support computer-driven downloads of data, load balancing, and a bunch of other neat things while maintaining backwards compatibility. We managed to build a system based on XML in a few months that we have been using ever since. Basically, all of our data is encapsulated inside of Business Objects which respond to certain methods. Our clients like getting data in XML, and it even works through firewalls. It was SOAP before there was SOAP. Now we are working on metadata. Allowing people to get information about the data in our databases is interesting, but it raises all sorts of new challenges (besides understanding Schema standards).
Why the Web Needs Groves is an article that XML heads might find interesting. It identifies some serious problems with the current XML programming model (eg, DOMs) and proposes an interesting solution.