Sometimes thumbnails of photos uploaded to the user profile can cause grief. Especially when you want to display these photos on a pubic website. Most of the times the picture will not be displayed on the public website after it's uploaded to the User Profile.
The reason this happens is because the photos in User Profile service are stored on the Personal Site in the SharePoint farm e.g. http://SP2010:8080/ User%20Photos/Profile%20Pictures/user_MThumb.jpg and by default the permissions on the Personal Site do not allow anonymous access.
To resolve the display issue, break the permission inherence on the Personal Site and provide "anonymous" permission to http://<Personal site>/ User%20Photos/Profile%20Pictures library where the photos are stored.