Not necessarily...

'@whoever' is the entire twitter name so isn't necessarily 'at' someone...but it does mean you want them to see it@

e.g. if I wanted to directly address you.

@inutero I can't believe you don't know how this works

or if I wanted to tell someone else, but have you see:

@odonoghue I can't believe @inutero doesn't understand how this works, the bell-end.

Posted By: Hertz van Rental, Jun 1, 14:56:19