[Plugin: Jetpack by WordPress.com] We're sorry, but we could not fulfill your request for /wp-c

I’m getting following error while trying to comment as non wordpress user

Error 403We're sorry, but we could not fulfill your request for /wp-comments-post.php?for=jetpack on this server.
You do not have permission to access this server. Data may not be posted from offsite forms.
Your technical support key is: XXXX-XXXX-XXXX-XXXX
You can use this key to fix this problem yourself.
If you are unable to fix the problem yourself, please contact wordpress at XXX.XXX and be sure to provide the technical support key shown above.

I honestly not sure where to start, so I’m posting it here…

http://wordpress.org/extend/plugins/jetpack/