What does CityDesk do? Looks like it provides a GUI front-end for a set of XML transformations. Not that that is a bad thing. It’s a good thing. People feel more comfortable with the “control” that they feel a WYSIWYG editor gives them. Personally, I get irritated from having to go over all the formatting and get it right. But it looks like Joel has combined the best of both worlds — kind of like XMetal does.
I have a similar system in place at work that let’s me edit a document without bothering with the formatting and produce printable copy from the same document. I can change the appearance on the fly — this is what XSLT is for. And, if you are into Perl, check out AxKit which will give you all these benefits for free. But, without the GUI front-end.