Avatars still weren't showing up for me in the new version at first. I managed to fix it by adding "forum/" in front of 'image.php' on line 49 in top_posters.php on the server.
PHP Code:
$avatarurl = 'forum/image.php?' . vbulletin->session->vars['sessionurl'] . "u=$top_poster[userid]&dateline=$top_poster[avatardateline]";
Hopefully that helps someone else, who's forum is installed at
www.website.com/forum