push notifications iPhone app - i.e. "pseudo background" app to check GPS location at regular intervals and save it on the phone or server. I understand iPhone OS 3 allows a server to push notifications to the app at regular intervals and therefore wake up the app, at which stage it would record the location.

Also needs to then check if the recorded locations are within certain areas on the map and report on this. This can be done server side.

Being able to also write/port the app on Android and Windows mobile would be a bonus but not a requirement.

Server side app ideally based on OpenSource tech - Ruby, Java, Python, etc.