The W3C Working Group on Internationalization released a best practices guide to Internationalization back in early April that is worthy of note. In short, it is increasingly important (when it comes to Web design) to specify the language within XHTML and HTML content. This is useful for a number of applications, according to the paper's abstract, from linguistically-sensitive searching to applying language-specific display properties.

"In some cases the potential applications for language information are still waiting for implementations to catch up, whereas in others, such as detection of language by voice browsers, it is a necessity today. On the other hand, adding markup for language information to content is something that can and should be done today. Without it, it will not be possible to take advantage of any future developments."

What this means is that specifying the language of a Web page is crucial if you want to take advantage of the current state of browser technology and any new advances as they are released.