In a sense that facility already exists - if members are prepared to insert their long/lat in their profiles and those interested have Google Earth installed (or an atlas).
To prove the point I have entered my co-ordinates in the 'interests' section of my profile.
However, and this is a big however, many people do not wish to reveal their exact whereabouts, and understandably so, whereas it doesn't worry me - my weather web site pins me down anyway.
An interesting thought though, marshall_42, as even if members only insert an approximate grid reference (say the local town or railway station) it could still be enlightening. It must though be voluntary otherwise we will have a host of people living at the north and south poles.