Reading about Peter Chernin's appointment to the Twitter board in Dalton Caldwell's "Twitter is pivoting" post, I came across mention of the dot reply, a seemingly handy way of replying to a user but having it go out all your followers. Hint: replying with an at only hits that user and any of your followers who are also following that user. It's Twitters way of controlling the echo chamber. Caldwell talks about power users knowing this shorthand which put me back a little as I've been on Twitter for over five years and, although having seen a few dot replies, I've never used it myself. A look at the Twitter documentation finds no mention of it. Indeed it's a Twitter hack formulated by users. But here's the kicker: it's a contextual thing. If I want to reply to someone and loop in all my followers I'll construct the tweet differently: "That guy @follower, messing with me again." Be conversational about it, cause apparently that's what Twitter is all about.
What Caldwell doesn't point out is that the dot reply breaks Twitter conversations. Perhaps Chernin wanted to get into a little bit of banter with the Twitter crew before breaking off and going his own way. I did get scientific and tested my theory with Jeremy, unknowingly to him, indeed breaking our conversation by using the dot. It makes sense if you're calling someone out, not so when you're right in the middle of a chat.
Dot replies are lazy shorthand. If your intention is to talk to a follower through your pack, think before you tweet.