Not like Foursquare does, the intention of GpsPing! is to notify recipients that you are physically passing by geographical locations that you have already set. You can find it useful in many ways. For instance, every day you are coming back from work, and you text your wife to let her know that you are almost there. With GpsPing!, you could create a notification for her, so maybe you are a mile away, and the text message will be automatically sent (if you confirm so!). Another option could be if you are a runner, and you want to track partial times. GpsPing! will let you set points within the route, so when you are passing by them, notifications are sent, and then 'offline' you can check how much you are improving your performance!.
So, GpsPing! will let you send notifications to your contacts from your selected geographical location, in a semi-automatic way(*). When you are physically at that location, or passing by it, GpsPing! will remind you about it, and will ask for your confirmation to send it. You can create as many notifications as you want, and for each one, you will provide the recipient (email or phone number), a message, and a location on a map.
As a side note, have in mind that the notification will be triggered when you are within a radius of 50 meters from the location you have set for it. Also, once it is triggered, it will remain 'disabled' for a period of 3 minutes, in order for it to be triggered again.
(*)Notifications are not fully automatic as they will ask for your confirmation to be delivered. This is for security reasons, as we don't want to generate 'spam', nor making fake calls. Apple, Inc. supports this approach.
Please have in mind the the application needs to be run at least on the background (taking advantage of iOS multitask), and can take some considerable battery charge.