I've already setup an account with gravatar, and uploaded a picture on it... but it's not showing up here in the stackexchange... Is there a step that I have overlooked?
Just so this question is answered:
In order to use a Gravatar on an SE site, one should make sure that the e-mail address associated with the Gravatar account is the same e-mail address that you used in your SE account.
If you have recently changed your Gravatar, it can take a few minutes before it takes effect. Some patience is needed.