The new "Player Info"-Meta Tags aren't xhtml compatible:
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=7" />
<meta name="ogame-version" content="3.0.0">
<meta name="ogame-timestamp" content="1314209283">
<meta name="ogame-universe" content="uni680.ogame.org">
<meta name="ogame-language" content="en">
<meta name="ogame-player-id" content="100147">
<meta name="ogame-player-name" content="HelpLess">
<meta name="ogame-alliance-id" content="0">
<meta name="ogame-alliance-name" content="">
<meta name="ogame-alliance-tag" content="">
<meta name="ogame-planet-id" content="33622072">
<meta name="ogame-planet-name" content="Homeworld">
<meta name="ogame-planet-coordinates" content="1:22:4">
<meta name="ogame-planet-type" content="planet">
Not urgent, but for cosmetics and validity. :-)