Link: Twitter Rolling Out “You Both Follow” Feature
Once this new feature is enabled on your Twitter account, when you visit another user’s profile you will now see who you have in common on their sidebar, right above the full list of people they follow. You can click a “view all” link to see the full list of mutual follows.
This is very similar to Facebook’s “Mutual Friends” feature. Read about the details in this posting.
by Adam Ostrow on @mashable