A grreat FAQ on XHTML is available, and I encourage all fellow web developers to read up. I found a few interesting things:

First read this:

strong>Why is it allowed to send XHTML 1.0 documents as text/html?

XHTML is an XML format; this means that strictly speaking it should be sent with an XML-related media type (application/xhtml+xml, application/xml, or text/xml). However XHTML 1.0 was carefully designed so that with care it would also work on legacy HTML user agents as well. If you follow some simple guidelines, you can get many XHTML 1.0 documents to work in legacy browsers. However, legacy browsers only understand the media type text/html, so you have to use that media type if you send XHTML 1.0 documents to them. But be well aware, sending XHTML documents to browsers as text/html means that those browsers see the documents as HTML documents, not XHTML documents.

Then read this:

Why is it disallowed to send XHTML 1.1 documents as text/html?

XHTML 1.1 is pure XML, and only intended to be XML. It cannot reliably be sent to legacy browsers. Therefore XHTML 1.1 documents must be sent with an XML-related media type, such as application/xhtml+xml.

Now in the source of that webpage, I see:

< ?xml version="1.0" encoding="UTF-8"?>
< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
<html xmlns="http://www.w3.org/1999/xhtml">

but Mozilla says:

Type:  text/html

Does anyone taste dogfood? Will the net ever move to towards xml? Not even the W3C feels it’s safe to move.

I don’t think we will ever see websites that say:

Type:  application/xhtml+xml

On a sidenote: Does anyone know what versions of Internet Explorer support this trick? Is it 5.0+? Or just 6.0?