"@" tag Suggestion

I think RockerChi submitted a clever suggestion.
Let me quote:
www.listal.com/suggestion/1581

Add an at "@" feature to tag friends/followers so you can respond to comments and it notifies the person. Very helpful for list comments.

The only problem is display names are not unique which would make this a little more tricker to implement

edit: I guess it could be based on username

Yeah. Usernames would be better because they are unique, besides they don't allow spaces and special characters which might be an issue in tagging.