WordPress Plugin: List all plugins that need updates in wp_footer()

list_plugin_updates.php

<?php
/*
Plugin Name:	Plugin update lister
Plugin URI:		https://gist.github.com/995560
Description:	Adds a table to your ´wp_footer()´ that lists all plugins that need updates. The plugin works out of the box.
Author:			Franz Josef Kaiser
Author URI: 	https://github.com/franz-josef-kaiser
Version:		0.1.
License:		GPL v2 - http://www.gnu.org/licenses/old-licenses/gpl-2.0.html

	(c) Copyright 2011 - 201X by AUTHOR

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
*/

// Secure: doesn't allow to load this file directly
if( ! class_exists('WP') ) 
{
	header( 'Status: 403 Forbidden' );
	header( 'HTTP/1.1 403 Forbidden' );
	exit;
}

function wpse18476_check_plugin_updates()
{
    // Assuming that plugins have properly named folders:
    $update_plugins = get_site_transient('update_plugins');
    $update_plugins = $update_plugins->response;

    echo '<style>
    #plugin-lister { width: 100%; margin-bottom: 1.5em; }
    #plugin-lister caption { font-size: 1.5em; font-weight: bold; margin: 1em 0; }
    #plugin-lister { text-align: left; }
    #plugin-lister tr th.name, tr td.name { width: 40%; border: 1px solid #ddd; border-top: none; border-left: none; }
    #plugin-lister tr th, tr td { width: 15%; border: 1px solid #ddd; border-top: none; border-left: none; }
    #plugin-lister tfoot tr th, #plugin-lister tfoot tr th.name { border: none; border-right: 1px solid #ddd; }
    </style>';
    echo '<table id="plugin-lister">';
    echo '<caption>'.__( 'All Plugins that need updates' ).'</caption>';
    echo '<thead>';
    	echo '<tr>';
    		echo '<th class="name">'.__( 'Name' ).'</th>';
    		echo '<th>'.__( 'Curr. Version' ).'</th>';
    		echo '<th>'.__( 'New version' ).'</th>';
    		echo '<th>'.__( 'Repo Link' ).'</th>';
    		echo '<th>'.__( 'Download' ).'</th>';
    	echo '</tr>';
    echo '</thead>';
    echo '<tbody>';
#echo '<pre>'; print_r($update_plugins); echo '</pre>';
    foreach ( $update_plugins as $plugin_name => $plugin_data )
    {
        $plugin = explode( "/", $plugin_name );
        $folder = $plugin[0];
        $init_file = $plugin[1];
        $data = get_plugin_data( WP_PLUGIN_DIR.'/'.$folder.'/'.$init_file, false, true);
#echo '<pre>'; print_r($plugin_data); echo '</pre>';
        $name = $data['Name'];
        $old_version = $data['Version'];

        echo '<tr>';
        	echo '<td class="name">'.$name.'</td>';
        	echo '<td>'.$old_version.'</td>';
        	echo '<td>'.$plugin_data->new_version.'</td>';
        	echo '<td><a href="'.$plugin_data->url.'">'.__( 'Go' ).'</a></td>';
        	echo '<td><a href="'.$plugin_data->package.'">'.__( 'Go' ).'</a></td>';
        echo '</tr>';
    }
    echo '</tbody>';
    echo '<tfoot>';
    	echo '<tr>';
    		echo '<th class="name">'.__( 'Name' ).'</th>';
    		echo '<th style="width: 15%;">'.__( 'Curr. Version' ).'</th>';
    		echo '<th style="width: 15%;">'.__( 'New version' ).'</th>';
    		echo '<th style="width: 15%;">'.__( 'Repo Link' ).'</th>';
    		echo '<th style="width: 15%;">'.__( 'Download' ).'</th>';
    	echo '</tr>';
    echo '</tfoot>';
    echo '</table>';
}
add_action( 'admin_footer', 'wpse18476_check_plugin_updates', 99 );
?>