I'm the President of a large regional marine aquarist club in the Mid-Atlantic and we had a similar thing come up a few years ago. Because of our privacy policy (which I authored), we steered clear of producing and maintaining a similar members map publicly using Google Maps. However, we did not prevent another member from our community from voluntarily creating and maintaining a map using information provided by other members with their express permission.
While I never used it, others found it useful. However, the task of maintaining the resource can be substantial for one person given that we are a mobile and sometimes transient community of over 3,000 members in our region.
People were able to provide general location information (city, state type information) or could get more specific (intersection of x and y) and it would be put in the system along with their screen name.
The idea lasted for about 4 years before the member who was maintaining it dropped out of the hobby.
So, technically, it's easy to achieve, but there are other obstacles that can make it difficult to implement and, even more importantly, to maintain over the long run.
Just my two cents.