Answer: It's a new feature that allows to insert a small picture of your car, dog, cat, yourself, etc, as a way to identify yourself. I have inserted a small picture of my car as an example.
Question: So how can I do that?
Answer: While filling out the questions required to post a new question or reply, you will see that a new field has been added call Avatar URL. Insert the URL to your picture, here is an example.
If you already use Photobucket to store your online pictures, highlight the picture you wish to use and click on the "Direct Link" option. That action will copy the URL into your computer's memory so all you need do is paste it into the new Avatar URL field.