Sounds pretty alarming, actually. I'm a big fan of Foursquare but have some rules of my own about when and how I use it, and am rather antisocial regarding whose requests I accept for friendship on the Foursquare network.

For example, when I'm with my kids, I rarely ever check in to public venues as I value our privacy in those situations, and like to focus my attention on my kids anyway. When I'm out, I am always conscious of the broadcast nature of a checkin too, so if I just want to put my head down and focus on some writing or other work, I'll skip a checkin or use the "don't tell your friends" option if I'm jonesing for a mayorship of that particular venue.

More importantly, I am far more strict about my friend acceptance policy than on other social networks. On Twitter I follow people I don't know, on Facebook I know I'm friends with people who I wouldn't recognize if they came up to me on the street and said "hi", and on LinkedIn, I've become more lax because of the tremendous benefit of a large circle of connections on that site.

On Foursquare, however, my rule of thumb is that if it's not someone I would invite into my house for a cup of tea, I don't want to share my geolocation checkins with them. So I only accept about 40% of the friend requests I receive on Foursquare so that I know when it sends out a message about me just getting to Amanté Uptown or popping into The Med for happy hour, I know it's only my real friends who get that information.

Even with that, however, I was surprised when I reviewed my own friend list on Foursquare that there were a few people who were unknown to me. Sure they live in my area, but that's not a smart reason to tell them my location 3-4 times a day, is it?

To go through my list, I went to Foursquare.com and logged in...

Once logged in, the "Friends" tab yields three different categories of friends:

You'll want to review "Friends" here, though if you have pending requests, it's an easy way to accept or reject them en masse.

Once you're looking at the list of your friends, identify one with whom you don't want to connect and you'll see their entry is similar to this:

I'm sure Courtney is a lovely person, but I don't remember who she is and therefore she's off my list. To do that, I simply move the cursor to the right of the "pings" checkbox, where a new icon magically appears:

As you might expect, clicking on the "X" removes them from your Foursquare friend list. Well, almost. You still have to confirm that's what you seek...

B'bye Courtney! Go through your own Foursquare list (or the friends list of any other geolocation checkin service you might use, like Gowalla) and make sure that you know each and every person on that list too. It's just smart.

And as an aside, the fact that I can't have Facebook Places checkins go to a subset of my Facebook friends is one reason I rarely, if ever, check in to locations or venues within the Facebook universe. Maybe at a tradeshow...