With the rise of twitter, it has become now fairly commonplace to use the @Username format to reply to someone. I was wondering if there would be a way to have the system detect that use to 1) create a hyperlink to the mentioned person's profile page and 2) to create a notification (à la twitter) to the mentioned person (possibly on a dedicated page instead of via email).

and

http://blog.stackoverflow.com/2010/09/new-global-inbox/

3. comments which reply using @username notation to an earlier comment you left
• Ah, neat I missed that. Thanks! Mar 31 '11 at 17:06
• What happens if for example me and Jonas Meyer comment in a post and someone does @Jonas? Mar 31 '11 at 20:05
• @jonast they would have to enter it as @jonast not @jonas Mar 31 '11 at 21:54
• Why aren't notifications to multiple users within the same comment supported? This is a (nonexistent) "feature" that people use all the time on math.SE. (It would be handy if it and useful if it actually worked.) Apr 1 '11 at 3:06
• Sometimes @usernames hyperlinks (it goes blue), sometimes it does not. When it does not, does it mean that the reply, did not work, will the person be notified that he or she was mentioned? Dec 4 '16 at 0:31