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.
http://blog.twitter.com/
Maybe not the best change in the world, I get a lot of followers from people that see people replying to me on twitter