Twitter made a small update in settings of notices section. This prevents an user from getting updates or tweets from your friends that start with @Username, if you were not following him/her. To be more clear you cannot see any more @replies in your twitter stream unless until you follow both the sender and recipient of the tweet.
According to Twitter blog..
We’ve updated the Notices section of Settings to better reflect how folks are using Twitter regarding replies. Based on usage patterns and feedback, we’ve learned most people want to see when someone they follow replies to another person they follow—it’s a good way to stay in the loop. However, receiving one-sided fragments via replies sent to folks you don’t follow in your timeline is undesirable. Today’s update removes this undesirable and confusing option.
I generally like @reply as it enables us to check out what our friends are discussing about and you can join their conversation if you like. But with this update, you won’t get all the @reply messages from any users you were following. This reduces chances of meeting new people as you don’t get any tweets about people whom you are not following.
If you don’t like this change, tweet about it using the hash tag #fixreplies, which is currently the top trending term on Twitter.
Follow me on twitter @pcsbox – http://twitter.com/pcsbox for more updates..