"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."
Biz, via the Twitter blog.
Basically, this is saying if I follow @a and not @b, I’ll never see @a’s tweet saying: “@b you’re brilliant, everyone should follow you!”
This feels very wrong from a discovery perspective. More than half of the people I currently follow on twitter I found organically through @-replies from someone I was already following. Now where am I going to find new people?