In "hooks-filters.php" on line 36 it should read:
$content_type = '<meta http-equiv="Content-Type" content="' . get_bloginfo( 'html_type' ) . '; charset=' . get_bloginfo( 'charset' ) . '" />' . "\n";
Notice the ';' character. Currently rendered HTML looks like this:
text/html charset=UTF-8
and should look like this:
text/html; charset=UTF-8
This confuses IE8 and it renders it as Western European if you have it enabled.