I like this actually. There've been a few times in past where I've stumbled across a profile randomly and just happened to notice one (or even more, occasionally) of my friends in their friends list or shoutbox, I think it'd be pretty cool for it to automatically show the shared friends if there are any.
It'd be good to show I agree, but I don't think it should replace the existing friend space. Maybe just like a little icon or something in the corner, and when you hover over it it says "This user is already in your friends list" or something? Or it could have text at the side (like the "Listening Now" text) that says "Mutual Friend"? Maybe? Possibly? XD
Good idea! I just don't want it to be there instead of the normal friends section. It'd be redundant when no friends were shared.
I too would like the groups a person leads listed first. And by lead, I don't mean only those they actually created, but also the ones they've taken over from or added by someone else.
Go to the dog of a site facebook and it's there, also that move would fan the flames of anti-lastbook resistance as it would be seen as a shift to lastbook.
Mutual friends shown first on a user's profile