Latest on twitter:
"4. When a user has connected their account and is currently logged in on your site, the application must show the profile picture and name of the user in a visible place on the page. This profile picture should be no smaller than 16x16 pixels and should include the Facebook “f” favicon in the lower right corner. If the profile picture is too small to position the icon over the lower right corner, you can position the favicon to the right of the picture."
Additional Policies Governing Facebook Connect - Facebook Developers Wiki
