How does the User card work?
Why has the style of the Gravatar icon display changed for SO, and why is it inconsistent?
Note that the first two icons have a shadow, while the 3rd does not.
( If you're accepting votes, I vote for no shadow. My Gravatar has transparency and is designed to blend in with the page - excepting for the huge letters of my initials in red/orange smack dab in the middle of it ;)