Glympse is a real time location software that allows you to share your location with twitter, facebook, by e-mail or via a number of other social networks. It is simple and intuitive to use. Connect your facebook, twitter and other services with the application. When you are heading to work or to the mountains for a ski trip you can start to share your location in real time. You can set the amount of time that the location is shared.
This is better than google latitude, foursquare and other services because it requires nothing from the receiver of this location sharing offer. Instead they simply click a link and they are kept up to date with your location progress.
The flexibility of this service gives the user good control therefore fearing for your privacy is not so relevant.
What I would like to see in future versions is the ability to play back the route we have taken. I would like to playback the train trip from one city in Switzerland for example.