The new Timeline allows you to hide the friends list by going to friends tab and change the privacy to "Only me", but it still shows those friends in common .
Is there a way I can hide them?
Although there is no control to hide this, it will only show a mutual friend to someone if one of the two people's friend lists are already visible. So if you hide your friend list, someone visiting your timeline will only see mutual friends that have their friend list visible to that person. So although Facebook makes it easier, the visitor can already tell that you and their other friend are friends by checking their other friend's friend list. If Facebook did not already display it, someone could just write a script to get the same information.