I’ve long been interested in the positive power of gossip to strengthen networks and share social mores.  The report “Communications: some lessons from the New Deal for Communities programme” concludes that:

The development of positive word of mouth networks provides a strong
base of awareness and a means of identifying and addressing problems.
Word of mouth communication between residents is one of, if not
the most effective means of communication and encouraging resident
engagement.
– Some word of mouth communication will occur naturally as the
programme develops however there is a need to facilitate its progress
by encouraging all residents to share their experiences with their friends

and by training a group of dedicated residents to act as ‘ambassadors’ –
people who will get messages out to the community, answer questions
and quash rumours.

And also cautions:

For all the importance of word of mouth communication, local activists
with negative opinions can be very damaging – word of mouth
communication can also be negative.
– Communication strategies need to be prepared to counter negative
‘word of mouth’ – by picking up local intelligence and ensuring local
champions counter unfair negative commentary.

Besides what the report says about press relations the lessons seem to be that good comms means building good relationships with the right people, putting the right knowledge into the right networks.   That is also largely the approach to take if you want to succeed on the social web.