Question: How can i make my application start on the iPhone startup?

Answer: 
You asked this question on 10th August 2010.

Now it's 13 November 2012. I'm adding this answer for future people who have the same question.

Now in iOS 6. There is a built in feature called guided access. You can achieve this feature using guided access. Still now you can't do this through code.

Please check these links:

[enable-guided-access-ios](http://osxdaily.com/2012/09/25/enable-guided-access-ios/)

[tip-how-to-turn-on-guided-access-in-ios-6-put-ipad-into-guest-user-mode](http://www.macgasm.net/2012/09/20/tip-how-to-turn-on-guided-access-in-ios-6-put-ipad-into-guest-user-mode/)
Only some very specific background applications can be started right from the iphone startup.
This includes VOiP applications for instance:

*"Including the voip value in the UIBackgroundModes key lets the system know that it should allow the application to run in the background as needed to manage its network sockets. **An application with this key is also relaunched in the background immediately after system boot** to ensure that the VoIP services are always available."*

As taken from:

<http://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html#//apple_ref/doc/uid/TP40007072-CH5-SW15>