Now, when you are writing a status update and want to add a friend's name to something you are posting, just include the "@" symbol beforehand. As you type the name of what you would like to reference, a drop-down menu will appear that allows you to choose from your list of friends and other connections, including groups, events, applications and Pages. Soon, you'll be able to tag friends from applications as well. The "@" symbol will not be displayed in the published status update or post after you've added your tags.
Really similar to how tagging works in photos but also tore a page right from Twitter's play book. Also going to have to see if it actually takes off and people start using it...via Facebook Blog: Tag Friends in Your Status and Posts