blavatars.php

<?php
/*
 Plugin Name: Blavatars
 Plugin URI: https://gist.github.com/1724438
 Description: Use Gravatar as a blogs avatar (Web Clip, Favicon, ...)
 Version: 0.1
 Author: Matthias Pfefferle
 Author URI: http://notizblog.org/
 */

add_action('wp_head', 'blavatar_header');

function blavatar_header() {
?>
  <link rel="apple-touch-icon" href="<?php get_blavatar(57); ?>" />
  <link rel="apple-touch-icon" sizes="72x72" href="<?php get_blavatar(72); ?>" />
  <link rel="apple-touch-icon" sizes="114x114" href="<?php get_blavatar(114); ?>" />
  
  <link rel="icon favicon shortcut" sizes="16x16" href="<?php get_blavatar(16); ?>" />
<?php
}

function get_blavatar($size = 90) {
  echo get_the_blavatar($size);
}

function get_the_blavatar($size = 90) {
  return "//www.gravatar.com/avatar/" . 
           md5(strtolower(get_bloginfo("admin_email"))) . "?s=" . $size;
}

Removed the http: from line 28, Firefox was complaining of insecure images now I've got https set up.