I have yammer for my colleagues and twitter for my friends and online acquaintances. I do wish there was a location specific twitter that ran, like yammer, through a desktop or iphone/android interface that was aware of my location and could be sponsored by a business.
for instance i am in sBux in union square – and need help with a java project. I would love to be able to shoot out a twitter that would only reach the people in this location to see if there is a java pro anywhere near that i could ask a question to.

user profiles would be tied to either twitter or facebook and the service would be tied to the business that owned or otherwise occupied the location if there was one.

those with the application could opt out for specific locations or all locations to remain anonymous and tracking would not happen between the locations. In other words – if you walked into sBux, the application nor the users would be unaware that you just came in from filene’s basement or mcDonalds next door. it just knows that you are here now