We’ve seen attempts at building a social network inside of Google Earth, such as YoubeQ, and now we have one that’s built entirely in Google Street View.
Wallit allows you to create a virtual “wall” anywhere on earth that you’d like, which others can then come write on.
The twist is that you need to be physically near the wall in order to write on it, which means you need the iPhone application in order to make much use of it. You can browse walls on their website, but can only interact with them if you’re mobile. Other mobile applications are coming “soon”, for what that’s worth.
You can learn more at wallitapp.com.