Looks like Twitter is on a feature release spree with several new releases coming up in the past few weeks. Twitter had just released some official Twitter retweet buttons yesterday and today they have released a few new features including type of lists you are part of, which friends of yours are following a certain profile and also common followers between you and another user.
When you visit a Twitter profile of a user, you will now be able to see which of your friends are following that particular user as seen in the screenshot above. You can also click on the Green retweet button to block Retweets of a user from appearing in your timeline.
In addition to that users will also be able to see which followers are common between both the profiles in the sidebar as seen in the screenshot above. You can see all the users that both of you follow in common by visiting this URL http://twitter.com/techiebuzzer/follows_in_common, just replace techiebuzzer here with the name of the user you want to check.
Along with these new features, Twitter is also displaying different Twitter lists categories a user is included in, which shows what type of lists a user is part of. This features was seen by an author on the fresher.com blog. The Twitter Lists feature is not active anymore, so there is no information on how Twitter is generating this information.
These are the only visual changes I could see now. However, I hope that Twitter also provides an option to mute users without unfollowing them for a short period of time .