Another couple of comments on location-aware systems.
First an update to my last post - Foursquare has a setting so that it opens on Places and not Friends by default. This is much better, but doesn't change what is presumably the way the Foursquare designers expect it to be used.
Next is that a few people have put together systems that show hot locations, using the rather unscientific method of taking check ins from the last half an hour to get round the lack of a check out option. An example of the is MisoTrendy which combines a witty name with a simple mashup between Google Maps and Foursquare. It shows "trending" venues on a map.
Unfortunately the main information you can take from this is that very, very few people actually check in anywhere at all. Edinburgh only has occasional traces of activity, even London has only 15 people currently checked in. Checks on other major cities where it is not the middle of the night showed equally low levels of activity.
So I fear that anybody trying to use wheretheladies.at is likely to continue to be sad and lonely.
Update: Just found Ratio Finder which identifies ratios of the sexes in locations as long as you are in San Francisco or New York, based on the much more amusing Wee Places which draws maps of your checkins with some cool animations. Is it long-term useful? Probably not, but it is pretty and briefly amusing. I suspect that it proves the old wisdom of the third place: home, work, and somewhere else you hang out.