Apparently, Firefox 1.5 will included something call E4X. It is an extension that supports easier manipulation of XML. Kurt Cagle has a very nice introduction, Objectifying XML – E4X for Firefox 1.1.
Suddenly, ECMAScript has better tools for dealing with XML than any other environment I know. Those tools will certainly make a lot XML manipulation code a lot clearer. Just as soon as it is supported by all the browsers, that is.