In the following picture, Gil Devora came by earlier and left a picture saying "Waiting to meet Robert Scoble" and you can see how many people start leaving notes replying to what he did.
Just like Facebok, Twitter, Google +, etc. if there is a lot of information within 50 meters, it will give you the newest information 1st and work backwards. Right now, they opened it for everyone. Everyone can see everyone because of web content, but at a later stage, one will only be able to see friends by either Facebook Connect or by your address book, etc. and they can leave notes to 1 person, a group, or Facebook friends, possibly leave notes to only Google+ friends or acquaintances if that's what they use. This app is excellent at museums. One would see a lot of notes left by other people and they can leave notes. This app is great at festivals, concerts, and as you'll see in the following video, the app being used while shopping, at restaurants, etc.
The volume of this video is really low, you would have to crank the volume. What I did was I put Closed Captions on so I can read it. Watch the video: