Custom avatars in wordpress comments?

by

Three simple steps to generate a Facebook Avatar:

  1. Create an extra field in your comment form for the user’s facebook
    profile (see e.g. WP Engineer for a code example and how to)
  2. If the user filled out this field, get the facebook avatar
    (see this question)
  3. Replace the WP avatar with
    your facebook avatar if a fb profile url is set

All together in this Gist (PHP5.3 required!). Tested with WP3.5 and FireFox/Chrome

Hint: It is strongly advised to read the code comments. There are several informations how to configure the plugin e.g. in the functions.php.