What is a gravatar?
A gravatar, or globally recognized avatar, is quite simply an image that follows you from site to site appearing beside your name when you do things. Avatars help identify your posts on blogs and web forums, so why not on any site?
More information here.
I just added this service to joomla comment. I followed this excelent tutorial and changed it a little bit :) In joomlacomment beta1 you will see in backend the option to use avatar (if you have community builder) and gravatar. The trick here is. You can use both at the same time. If you have community builder, then we will look first for cb profile image, if there is nothing, then we look for gravatar image. If gravatar image is there - we show it, if not, then we show the standard CB photo for no image.
When will joomlacomment 4.0 beta1 be published? I suppose, by the end of the week. Still have to make few changes to the code. The new web site offering you to advertise through joomlacomment must also be ready with beta1. So stay tuned! :)