If you’re a Twitter user, you’re used to @ tags. When you reply to a Tweet, you put @username and then type your reply. When you ReTweet someone, you use @username, as well.
The @ symbol was used on blogs long before Twitter came around, so that people could address specific commenters directly.
Now, Facebook is jumping on the @ bandwagon. If you want to reference another Facebook member in your update, use the @ symbol and start typing in their name. The twist is that the @ symbol won’t appear in the update, but it will hyperlink the name of the person you’ve tagged.
Additionally, those who’ve been tagged will get a notification, and they’ll be able to remove their name from your update.
http://blog.searchenginewatch.com/090911-155551
