We can't say what we know for sure what the long-term effects of using a mobile phone are. there are concerns of the radiation emitted from cellular devices because they are right next to your brain. Of course there are arguments on both sides. Still, if that has been a concern for you, someone has made an App that, according to the makers, minimizes your exposure to this radiation.
The application, in the words of the developer, "monitors and analyzes your mobile phone radiation so you can ‚Äö√Ñ√∫talk on‚Äö√Ñ√π as usual and receive smart prompts to avoid radiation just when you need to."
1) The installation process is relatively easy. First, you must have a jailbroken iPhone, which we have the iOS 4.2 instructions for here. If you're on 4.3, we'd wait for a more reliable jailbreak than any of the methods that are out right now.
2) Open Cydia and do a search for tawkon.
3) Now download and install the application and you are good to go.
Also, just in case you're interested, the developers have a petition going on so that they can get the app onto the App Store. We have no idea how much luck they will have as releasing this app is basically saying "This phone can kill you."
We also heard that the developer, Gil Friedlander personally emailed Steve about the App. Jobs' response? "No Interest." In his usual short fashion. Whether the email was real, we don't know.