cc-to-wp-feeds.php

<?php
// Adds Creative Commons license to WordPress RSS feeds

// Modify this for your site & license
$feed_license = array(
	"moduleNamespace" => 'xmlns:creativeCommons="http://backend.userland.com/creativeCommonsRssModule"',
	"ccNamespace" => 'xmlns:cc="http://creativecommons.org/ns#"',
	"link" => "http://creativecommons.org/licenses/by-nc-sa/3.0/",
	"ccName" => "Creative Commons BY-NC-SA",
	"years" => '2003-'.date("Y")
	);


// RSS 2.0
function rss2_ns_additions() { // namespace additions
    global $feed_license;
    echo $feed_license['moduleNamespace']."\n";
}
add_action('rss2_ns','rss2_ns_additions');

function rss2_head_additions() { // head additions
    global $feed_license;
    echo '<copyright>Copyright '.$feed_license["years"].' ';
    echo bloginfo_rss('name');
    echo '</copyright>'."\n";
    echo "\t<creativeCommons:license>".$feed_license['link']."</creativeCommons:license>\n";
}
add_action('rss2_head','rss2_head_additions');

function rss2_item_additions() { // item additions
    global $feed_license;
    echo "\t<creativeCommons:license>".$feed_license['link']."</creativeCommons:license>\n";
}
add_action('rss2_item','rss2_item_additions');



// RSS 1.0 (RDF)
function rdf_ns_additions() { // namespace additions
    global $feed_license;
    echo $feed_license['ccNamespace']."\n";
}
add_action('rdf_ns','rdf_ns_additions');

function rdf_head_additions() { // head additions
    global $feed_license;
    echo '<copyright>Copyright '.$feed_license["years"].' ';
    echo bloginfo_rss('name');
    echo '</copyright>'."\n";
    echo "\t<cc:license rdf:resource=\"".$feed_license['link']."\" />\n";
}
add_action('rdf_header','rdf_head_additions');

function rdf_item_additions() { // item additions
    global $feed_license;
    echo "<cc:license rdf:resource=\"".$feed_license['link']."\" />\n";
}
add_action('rdf_item','rdf_item_additions');



// Atom
function atom_head_additions() { // head additions
    global $feed_license;
    echo "<link rel=\"license\" type =\"application/rdf+xml\" href=\"".$feed_license['link']."rdf\" />\n";
}
add_action('atom_head','atom_head_additions');

function atom_item_additions() { // item additions
    global $feed_license;
    echo "\t\t<link rel=\"license\" type =\"text/html\" href=\"".$feed_license['link']."\" />\n";
}
add_action('atom_entry','atom_item_additions');


// RSS 0.92
function rss_head_additions() { // head additions
    global $feed_license;
    echo '<copyright>Copyright '.$feed_license["years"].' ';
    echo bloginfo_rss('name');
    echo ', '.$feed_license['ccName'];
    echo '</copyright>'."\n";
}
add_action('rss_head','rss_head_additions');