I just did that but it did not work.
Explaining better, first, I tried to add a Gravatar at the Edit Profile by add a URL address. It did not work. After that, I left that field in blank at Edit Profile and then, signed in at Gravatar.com, using the same address I have at my website. But the Gravatar is not showing.
Please take a look at http://www.chutecerteiro.com.br/?p=297. My user is Chutecerteiro and at that web address I think it is supposed to appear my Gravatar in the answer I gave to the user, right?