Here is a patch for the [[plugins/meta]] plugin. It adds the possibility to define the language used for a page, with [[meta lang="ja"]] It doesn't insert the langage information in the xhtml meta elements, but defines a LANG variable to use in the templates, for example with fr" xml:lang="fr"> This way also allows to define a language for a subset of the final page, with custom templates and inclusion. This may be useful for sites with a few pages in different languages, but no full i18n. 
--- meta.orig.pm  2007-07-27 00:19:51.000000000 +0200
+++ meta.pm       2007-08-05 22:37:40.000000000 +0200
@@ -11,6 +11,7 @@
 my %permalink;
 my %author;
 my %authorurl;
+my %lang;
 
 sub import { #{{{
        hook(type => "preprocess", id => "meta", call => \&preprocess, scan => 1);
@@ -100,6 +101,11 @@
                $meta{$page}.='\n";
        }
+       elsif ($key eq 'lang') {
+           if ($value =~ /^[A-Za-z]{2}$/) {
+               $lang{$page}=$value;
+           }
+       }
        else {
                $meta{$page}.=scrub("\n");
@@ -131,6 +137,8 @@
                if exists $author{$page} && $template->query(name => "author");
        $template->param(authorurl => $authorurl{$page})
                if exists $authorurl{$page} && $template->query(name => "authorurl");
+       $template->param(lang => $lang{$page})
+               if exists $lang{$page} && $template->query(name => "lang");
 
 } # }}}
[[tag wishlist patch plugin/meta translation]]