From decoded.php, for context:

    /**
     * ===WORDPRESS PHARMA HACK ANALYSIS===========================================
     * ============================================================================
     *
     * Patrick Adair [ patrick AT ionpublications DOT com ]
     * 
     * For the uninitiated, there's been a rather-nasty hack making its way across 
     * a number of prominent websites hosted with Wordpress called the "pharma 
     * hack"; named so because it hijacks your search results in Google, et al. to 
     * show obviously-spoofed results for Viagra and other generic medications 
     * that we see spammed all the time across the internet.
     *
     * As you, the reader, can rightly imagine, Wordpress blog owners were scared 
     * out of their minds and worked quickly to remove the hacks from their sites, 
     * finding the necessary codes sometimes hidden deep inside of their plugins 
     * and striking only when search engines and automated crawlers of any kind 
     * hit the site.
     *
     * On the 24th of November, 2010, we noticed that one of our sites, Science 
     * and Supermodels [ http://www.scienceandsupermodels.com ] was hit by the 
     * hack, and after a few times of playing cat-and-mouse with it (delete the 
     * injected code only to have it re-appear in the same place 30 minutes later), 
     * we were able to remove it entirely and all was well.
     *
     * But I had an interesting idea. To my knowledge, at the time of this writing, 
     * all of the accumulated knowledge on this hack was simply removal techniques 
     * for non-technical users (which, admittedly, is most of Wordpress' userbase 
     * so far as I can tell - the consequences of making it so gorramn easy to 
     * install). I decided that it would make an interesting project to break apart 
     * and analyze the injected code to try and figure out what it was doing, and 
     * see if any good can come of that.
     *
     * Fast forward to 24 hours ago (December 20, 2010), and I've finally cleared 
     * up enough time to start meaningfully decoding and rewriting this script, and 
     * I hope that something useful will come of this - perhaps a security company 
     * can pick up on the groundwork I've laid here and figure out how to actually 
     * stop the bastards doing this.
     * 
     * What follows is a SIGNIFICANTLY re-written version of the script, edited for 
     * clarity and also to test my programming chops - the original was compressed, 
     * encoded in base64, and even then written in an absolutely incomprehensible 
     * fashion.
     *
     * I've tried to include as much information as I can - since the control 
     * servers are still active for this hack (at least at the time of this 
     * writing), I was able to get pretty accurate debugging and data on what its 
     * delivery method was, and those will all be included in my Mercurial repo
     * along with this file.
     *
     * Also, this is based off of only the version of the hack that our site got - 
     * it remains entirely possible that other mutations of the hack exist and I 
     * would be curious to see what they look like / do. If you have other samples 
     * of the code, please email them to me and I would love to see.
     *
     * So without further ado, I present the Wordpress Pharma Hack:
     *
     */