Couple of Months ago Facebook started a new tagging system in their Status updates and wall posts same like twitter. putting “@” in wall posts before your friends name would notified them in notifications about your wall posts. Now same features has been added into comments section by Facebook.
Facebook has made it really easy for reply to specific person you want in comments. For example if you wan to reply to a particular person in comments you would write @name and it would tag automatically the specific person.