Similar to Loopt iPhone App

The functions of this app are very simple. Members should be able to communicate with other members. We currently run a Social Network. The iPhone application we desire will allow our members to: 1. Use their login from our social network 2. Import their profile details into the iPhone app 3. Identify their location (via GPS) The functionality of the app will: 1. Identify other users connected through the iPhone app and they will be listed with the closest members on top. (user is x miles away) 2. Allow them to send messages to those who are online 3. If the user is offline, send the message to the user's inbox in our site. Our social network can communicate through an API for login and profile data purposes. There is complete documentation on the API.