I also agree that there should be a user map.
It should be based on users input into the city, state, and country field. Personally I believe this should wait until at least ES 1.3 because a state field to reflect the country is planned. This would make it easier for searching.
Rather than making it an app, it should be an addition feature of custom fields. Perhaps rename the custom field "country" to "location" considering that it will support states to reflect the country selected. The custom field "location" could then have an option to enable user mapping considering that it replies upon this custom field to map the user.
In terms of mapping it could show a Google Map with your location as well as other people who either live in the same city or a specification of how many miles to show from your location. Here's a
great example of how it could look like, although I'd imagine you folks would want it to have a different layout.
Keep in mind this example is for mountains, but the same principles could be applied to people. Notice how it relies on the advance search? The user map could theoretically be accessed from both the about section of the profile or the advance search.