The Twitter Blog has a great explanation of the “@” reply feature. I had been using it, but it can be confusing, as it’s easy to assume that they go to the target user only. The thing to know is that “@replies” are visible to all, much like replying to one participant in a group conversation (the analogy used by the Twitter folks.
To reply ONLY to one user – you use the “direct” feature by starting your message with “d” – as in “d usernamehere”.
