If you don't really want to upgrade to the iPhone 4, you may have been bummed to hear that iMovie would only work on the new smartphone. Thankfully, a hacker has announced that he has been able to get iMovie to work on jailbroken iPhone 3Gs handsets.
Apparently the hack is rather simply once your iPhone is jailbroken. According to David Rohman Torres, the trick is editing the info.pst file inside the app.
You have to set the minimum system requirement entry to 3.0.0 and then turn front-facing-camera to false. The app will then reportedly work on the 3GS.