I used to create a number of simple web pages in XHTML back in the days when we believed XHTML was the future. Recently, while going through and restructuring some of my old "online stuff", I learned that XHTML really isn't in a state that I'd want to use it any more:

* XHTML 1.0 and 1.1 are officially deprecated by the W3C.

* XHTML5 exists as a variant of HTML5. However, it's very clear that it's absolutely not a priority for the HTML5 working groups, and there's a statement that future features will not necessarily be supported by the XHTML5 variant.

* XHTML5 does not have a DTD, so one of the main advantages of XHTML - that you can validate its correctness with pure XML functionality - isn't there.

* If you do a 'view source' in Firefox on a completely valid XHTML 1.0/1.1 page, it'll redline the XML declaration like it's something wrong. Not sure if this is intended or possibly even a bug, but it certainly gives me a 'browser tells me this is not supposed to be there' feeling.

It pretty much seems to me XHTML has been abandoned by the web community. My personal conclusion has been that whenever I touch any of my old online things still written in XHTML, I'll convert them to HTML5.