Stowe Boyd writes this morning of the issues of geolocation tools and privacy. I have been an early adopter of Brightkite, Foursquare, Twitter geotagging, Fire eagle and Google Latitude. The only ones I use now are Foursquare and Twitter and even then not all of the time. Like Stowe I often zoom out to city level rather than being specific about my location. I don't automatically post locations to Twitter to try avoid annoying people with too much noise and only do so when I think there might be a chance of meeting up with someone.
My experience so far has been 100% positive with many serendipitous meetings that I wouldn't have had without letting people know where I am.
I am always surprised when people write as if they were victims of technology rather than in control of it - I guess it is a bit like email!