I recently traded my T-Mobile G1, with Android, for an iPhone 3G. I am hoping to get MoosTrax running on the iPhone, but unfortunately, even with push notifications, it might not be the same as the BlackBerry and Android versions. Here are some reasons why.
No automatic location updates
The iPhone OS does not allow applications to run in the background, which means MoosTrax cannot check your location and send it to the server at a fixed interval.
Push Notifications aren't the whole solution
MoosTrax could send a push notification to your phone, telling it to send a location update to the server, but unfortunately it requires user interaction. It wouldn't be too convenient to have your phone vibrating every few minutes asking you to update your location.
Initially, MoosTrax for iPhone will have support for sending location updates to the server manually when you open the application.
Hopefully, within time, Apple will make the push notification functionality more advanced so that MoosTrax can be as powerful as it is on other platforms, such as Android and BlackBerry. For now, stay tuned for the iPhone application. I am waiting to be approved in the iPhone developer program and then you should see the application in the iTunes store soon.