UPDATE 10:41pm: @Biz has updated the blog post about the updates to say that when someone is mentioned in a tweet, you still get those updates even if you don’t follow them. This would seem to keep things like #followfriday in place. I’m waiting on information regarding how the placement within a post effects if people will still see the update. (ex. if I put @username at the beginning, does Twitter think this is a reply)

The powers that be at Twitter.com have now decided that if you aren’t following somebody, you don’t want to see when someone you follow @ replies to them in a post. They will now remove that tweet from your stream.

We’ve updated the Notices section of Settings to better reflect how folks are using Twitter regarding replies…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…

full post

Note that they call this a “small settings update”

On the face of this, it would seem to be a logical update. If I’m not involved in a conversation, there isn’t much need for me to see that tweet. But what this really has done is eliminate any chance of discovering new people through followers. The biggest example of this is in the #followfriday phenomenon. Every Friday, hundreds of twitterers will post the names of several people they think that their followers might want to follow. Whether that’s interesting people, people that post funny tweets or most useful in my case, people in the same industry that you might not be following. I have begun to follow several people on the basis of #followfriday. I’ve met many interesting people who work in higher education because I’ve either seen them in a #followfriday post or seen a person I follow reply back to them.

What Twitter has really done is once again, misunderstood the way we use the @ system. I’m sure they really meant to it be a true “reply” function, but it has turned into much more than that. Your users utilize the system in ways you couldn’t imagine and made the service truly useful. But now, you have broken what made it special. You have broken the system by which you find new people to follow.