Note to self: if you do things like $('#home').load('xml/homepage.xml', function() { ... , you might think everything is working fine, because it will be ok in Firefox, but then Allen and Tracy will say “Hey, you, look at the page in Internet Explorer and Safari. It is broken.”
So apparently what you have to do is more like
$.ajax({
type: "GET",
url: "xml/homepage.xml",
dataType: "xml",
success: function(xml) {
and then, everyone is happy!