>>357

自動登録のはず。
ja.gravatar.com/support/what-is-gravatar/
>It is automatically included in every WordPress.com account and is run and supported by Automattic.

WordPress.comでログインした状態ならGravatarもそのまま使えるはず。
ja.gravatar.com/support/how-to-sign-up/
>you'll need to have a WordPress.com account and then authorize that account to connect to Gravatar.