GPS Tracking Application

We are looking to develop a multi-platform application (iPhone, Android, BlackBerry, WM7) that is used to record GPS inforamtion on the mobile device, and then transmit it to our servers. The key aspects of this project are: 1 - Simple, easy-to-use interface on the mobile devices 2 - Ability to run in the background (if the mobile platform allows) 3 - Ability to store data on the device when there is no GPRS/3G/WI-FI signal 4 - Ability to send data over HTTP POST and also via a TCP connection to our servers (verification over HTTP POST and GPS tracking data over TCP) We are currently finalising our web services API and TCP protocol, which should be completed in the next 7 days. The application (all platforms) must be able to handle sending data in compliance with the web services API and TCP protocol, plus it must be able to handle the server-generated replies (e.g. ACK messages, etc). There iwll be a number of settings within the application to control how often data is recorded (i.e. how often a tracking log is recorded) and how often tracking logs are sent (i.e. how often recorded tracking logs are transmitted to the server). There will also be username and password fields (for server-side verification), plus the application will also use the IMEI number of the mobile device as further verification. Please do not bother reply to this unless: 1- You have experience with cross-platform applications 2 - You also have experience with GPS applications