I spotted an explanation of the pitfalls of XHTML over on Don Box's Blog. He actually went to XHTML, and backed off. In the technical blog-verse, there's been an awful lot of hullabaloo about XHTML, but this document convinces me that not yet is the correct answer:

There are few advantages to using XHTML if you are sending the content as text/html, and many disadvantages.

In addition, currently, the majority (over 90% by most counts) of the UA market is unable to correctly render real XHTML content sent as text/xml. For example, point your browser at:

http://www.mozillaquestquest.com/

Only Mozilla, Mozilla-based browsers such as Netscape 6 and 7, and very recent versions of Opera such as Opera 6 are able to correctly render that site. (IE6 shows a DOM tree!)

Authors who are not willing to use one of the XML MIME types should stick to writing valid HTML 4.01 for the time being. Once user agents that support XML and XHTML sent as one of the XML MIME types are widespread, then authors may reconsider learning and using XHTML.

That's right - like it or not, IE has over 90% market share, so using XHTML at this point is telling over 90% of your potential viewers to kiss off. No thanks. Far, far simpler to just slap HTML out there, and wait for the tools to evolve.