If you really want up to date, then get O\'Reilly\'s book on XHTML. XHTML is the new language now that HTML is finished. It\'s a bridge to the freedom (and universal browser compatibility) found with XML.
XML in itself, however, is crazy complicated and should only be used for people looking to get highly involved and professional. For most any application, XHTML is easier and works almost as well.
-Eik