Twitter Now Testing Setting for Limiting Who Can Reply to Tweets

Twitter today announced that it has started testing new conversation settings that were first outlined earlier this year at CES.
A "Conversation Participants" option in the window where a tweet is composed will allow users to select who can reply to a tweet. Options include everyone, people you follow, and only people you mention.
The "everyone" represents how Twitter traditionally works and it's the default setting that's selected, while the other two options will limit replies. Tweets that hav