Data Used: This feature will send a hash of the user’s email address (if logged in to the site or WordPress.com — or if they submitted a comment on the site using their email address that is attached to an active Gravatar profile) to the Gravatar service (also owned by Automattic) in order to retrieve their profile image.
Data Used: Commenter’s name, email address, and site URL (if provided via the comment form), timestamp, and IP address. Additionally, a jetpack.wordpress.com IFrame receives the following data: WordPress.com blog ID attached to the site, ID of the post on which the comment is being submitted, commenter’s local user ID (if available), commenter’s local username (if available), commenter’s site URL (if available), MD5 hash of the commenter’s email address (if available), and the comment content. If Akismet (also owned by Automattic) is enabled on the site, the following information is sent to the service for the sole purpose of spam checking: commenter’s name, email address, site URL, IP address, and user agent.
Activity Tracked: The comment author’s name, email address, and site URL (if provided during the comment submission) are stored in cookies. Learn more about these cookies.
Data Synced (?): All data and metadata (see above) associated with comments. This includes the status of the comment and, if Akismet is enabled on the site, whether or not it was classified as spam by Akismet.