Just hold the home key (The only button on the front of the phone) for 10 seconds with the app you want to kill open and it will get restarted. That will do the trick. This should lead to longer battery life and a cooler phone.
I've noticed a number of people still hit this blog. I'm pretty sure that iphones now use that home button for screen capturing and the above advice won't help anymore.
So here is what to do now:
From the 3g on the thing to do is restart your iPhone by:
- Hold down the power button (top of the phone) until the slider comes up asking you if your sure you want to shutdown (This can take about 10 seconds).
- Just slide it to say yes and wait while it shuts down.
- When it's done shutting down push the power button again to start up again.
Everything should work better now and the heat should dissipate. Good luck!