This is a well-discussed and very important topic. Personally, presently I write XHTML for my web interface code, but lately I’ve started to stagger in my standpoint. For normal general web page design, what’s the gain? If you don’t extend the code with namespaces, use MathML, have your own DTDs and so on, why would you want to use XHTML?
An incredibly well written and interesting article that will make any web designer at least think twice about there use of XHTML.
Wandering the Interwebs 