Theme Support for WordPress 2.5
The function to add Gravatars to your theme is called: get_avatar. The function returns a complete image HTML tag of the Avatar.
The function is called as follows:
<?php
echo get_avatar( $id_or_email, $size = '96', $default = '<path_to_url>' );
?>
The parameters are:
* id_or_email (required): Author’s User ID (an integer or string), an E-mail Address (a string) or the comment object from the comment loop. Note: with most comment templates you can use $comment here, in order to display the gravatar of the commenter.
* size (optional): Avatar display size (max is 512).
* default (optional): Absolute location of the default avatar to use (used when the person has no email address associated with them). If this is left blank then the gravatar you see here will be used as the default avatar.