From what I have seen of other 'friends' .. its a case of creating your own 'presence' and communicating with others as you think appropriate and creating Groups for any localised projects you may have of your own and obviously inviting other 'friends' in where their expertise / knowledge may be useful.
The little I have used it, it seems to be good in helping to get some new takes on sites and some ideas.. from people I would never normally meet or communicate with.