The meta tag for content-type is little more than a fallback. If a content-type header is sent with character encoding specified, this will be used, at least by FF 3.5 and Safari 4.
Here, the charset of the meta tag will be used.
<?php
header("Content-Type: text/html;");
?><!DOCTYPE ...><html ...><head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8"/>
But if you first send this header, it doesn't matter what charset you specify in the meta tag.
header("Content-Type: text/html; charset=utf-8");
Using Safari, Firefox with the firebug plugin, and iirc IE8 as well, you can see what headers were sent by the server.