Twitter engineer Nick Kallen posted a tweet several hours ago saying the new 'You both follow' feature was starting to be tested. TechCrunch picked up on new feature being enabled noting only 10% of users are part of the test group.
'You both follow' is fairly self-explanatory, users are able to see people that the user and the other user both follow. The screenshot shows this feature is located just above were users are able to see who the other person is following. This simple feature basically allows users to follow people from similar communities more easily on the microblogging site.
This update can potentially mean the introduction of similar friend features found on other social networking sites such as Facebook. Facebook's friends in common feature is comparable to 'You both follow' and has existed for several years.
Twitter API engineer Marcel Molina also said in a tweet he has formed a team with Kallen "to build rapid prototypes". This potentially hints at further features that may expand on 'You both follow' like recommending people to follow based on who Twitter users are currently following. No time-frame was given as to when new features or when 'You both follow' will be available to all Twitter users.