Thanks for the answer, James.

Next question...

We're using poor-man's DHTML (Dynamic HTML transclusion) on our website (using a hidden iFrame as a buffer to bring external content in, then cloning the Nodes from the Iframe to a DIV in our page). This technique allows us to keep our header, footer, and menu loaded, while dynamically changing the Content DIV's content. (Don't worry, I've set up all the links so they can be followed by SE Bots and screen readers).

But, the iFrame is deprecated, so I did some looking around, and figured out that doing Dynamic XML transclusion is pretty easy. So, I'm learning XML right now, and plan to change our site over to XML as soon as I'm able, using the same type setup as we have now (basically, the site will look exactly like it does now, but the underlying infrastructure will be radically modified... somewhat akin to swapping out a mouse on an exercise wheel for a 454ci Chevy big-block V8 engine). XML transclusion will allow me to do some things that are impossible with HTML transclusion, and will be cross-browser compatible on all DOM2 compatible browsers (our site right now only works in IE 5.5 and up).

Now, to the question...
How well do the search engines handle XML pages?