A quick note to anyone who is using character entities (e.g. ©) in this, and finding them automatically escaped. The correct thing to do here is to use the createEntityReference method (e.g. createEntityReference("copy");), and then appendChild this entity between text nodes.
Example:
<?php
$copyright_text_1 = $this->document->createTextNode("Copyright ");
$copyright_text_2 = $this->document->createTextNode(" Alex Kaye 2009");
$copyright_symbol = $this->document->createEntityReference("copy");
$copyright->appendChild($copyright_text_1);
$copyright->appendChild($copyright_symbol);
$copyright->appendChild($copyright_text_2);
?>