Add a fake/faux oEmbed provider for DocumentCloud. Also adds a shortcode.

documentcloud.php

<?php

/* Faux DocumentCloud oEmbed
 * Embed documentcloud inline without using their provided embed code because it sucks
 * @usage Paste a Documentcloud link in your post and it will be replaced with an the proper code when published
 */
 /*
 * Example embed URL:
 * http://www.documentcloud.org/documents/693854-macalester-collge-letter-to-students-about-wells.html
 */

wp_embed_register_handler( 'documentcloud_oembed', '{^https?://www\.documentcloud\.org/documents/(?P<id>.+)\.html}', 'embed_documentcloud_oembed' );
function embed_documentcloud_oembed( $matches ) {
    $id = parse_documentcloud_id_from_url($matches[0]);
  $embed = "
        <div id='DV-viewer-$id' class='DV-container'></div>
        <script src='http://s3.documentcloud.org/viewer/loader.js'></script>
        <script>
          DV.load('http://www.documentcloud.org/documents/$id.js', {
            width: '100%',
            height: 500,
            sidebar:false,
            text: true,
            pdf: true,
            container: '#DV-viewer-$id'
          });
        </script>
        <style type='text/css'>#DV-viewer-{$id} * {box-sizing: content-box;}</style>
        ";
	return apply_filters( 'embed_dc_map', $embed );
}


/* 
 * Documentcloud Shortcode support
 * Borrowed from the argo project but dramatically simplified for our use: http://argoproject.org/documentcloud.php
 *
 */ 


function documentcloud_embed_shortcode($atts, $content){ 

    global $post;
    //$defaults = $this->get_defaults();
    
    extract( shortcode_atts($defaults, $atts));


    // we need a document ID or URL, or it's a no op
    if ($url && !$id) {
        // parse id from url
        $id = parse_documentcloud_id_from_url($url);
    }
    extract( $atts);

    // still no id? nothin doing
    if (!$id) return;
    
    # we only deal with integers
    $height = intval($height);
    $width = intval($width);
 
    return "
        <div id='DV-viewer-$id' class='DV-container'></div>
        <script src='http://s3.documentcloud.org/viewer/loader.js'></script>
        <script>
          DV.load('http://www.documentcloud.org/documents/$id.js', {
            width: '100%',
            height: 500,
            sidebar:false,
            text: true,
            pdf: true,
            container: '#DV-viewer-$id'
          });
        </script>
        <style type='text/css'>#DV-viewer-{$id} * {box-sizing: content-box;}</style>
        ";
}

/* 
 * Support/helper function for documentcloud embed/shortcode support
 */

function parse_documentcloud_id_from_url($url) {
    $regex = '{^https?://www\.documentcloud\.org/documents/(?P<id>.+)\.html}';
    $matches = array();
    if (preg_match($regex, $url, $matches)) {
        return $matches['id'];
    } else {
        return null;
    }
}
add_shortcode('documentcloud', 'documentcloud_embed_shortcode');

Use <script src="//s3.amazonaws.com/s3.documentcloud.org/viewer/loader.js"></script> to have this work on https URLs.