This always bothered me so I'm sort of glad they changed it. Now instead of seeing messages from people I follow to people who I don'nt follow, they will be hidden. If I follow both people, I'll see the communication. The downside of course is that I may miss some threads. Occasionally I would follow up on these one-sided conversations by clicking on the name of the person being replied to in order to see what I had missed. http://blog.twitter.com/2009/05/small-settings-update.html