Maybe it's not new to you, but it certainly is to me. The W3C finally sends their homepage as application/xhtml+xml (I use . It isn’t; I replaced it with samp for this (actually for everything), is that correct?)CODE. If you live close to these guys, give them a beer ;).
I was actually wondering about samp as well. What should we use for these kind of technical terms? Especially in my Dutch blog I feel I need to mark them up, using a language attribute as well.
I decided to stick to samp. I like it, it's easy to maintain, it's searchable and it differentiates itself from the surrounding markup.
And you are right about the lang (xml:lang) attribute I think. On Dutch sites I always use it on English abbreviations, so for the abbr and acronym elements.
I always wondered about the lang attribute for abbreviations. Take the term HTML. It is of course english, but it is not spelled in english letters (here in Germany). Wouldn't the lang="en" attribute force a smart screenreader to spell it out using english letters?
I am still not sure.....