Thanks to helpful input from Matt Schlosser, just sent in the following suggestion to Facebook...
(PS go collaborative production / nascent group forming... posted the q a week or two ago, it sat there for a while, and then eventually it found its way to someone who was interested in it and could add value on top of it)
Allow users to share status updates with friends only in a certain geography
All the time I blast things like, 'anybody want to come to the movies tonight?' Clearly, this message is intended only for my friends who live in the same city as me, and would be great to be able to spare the rest of my friends the (mostly) irrelevant spam.
More broadly, give users more control in targeting the content they publish (to geographies, interests, I'd even add a hash tag system). Key problem Facebook is trying to solve is discovery -- how do you match the incredible mass of content users publish with the often small groups of people to whom any given piece is interesting? Answer... the same way Facebook does everything: collaboratively, by letting users do it for them.
With regard to content broadcast, user 'privacy' settings aren't just about privacy... they're about targeting. Users are in the best position to know who will and will not be interested in the content they publish, and given they're sharing the content for some reason, they have every incentive to try targeting it correctly. Facebook should tap that potential"