Out of the box I'm getting a 400 error for the admin gravatar on the admin slideout panel. Here's the culprit from my layout.master:

<img width="40" height="40" src="http://www.gravatar.com/avatar/64e1b8d34f425d19e1ee2ea7236d3028.jpg?r=G&amp;s=40&amp;default=http%3a%2f%2fwave%2fData%2fSiteImages%2fanonymous.png" alt="Gravatar">