Will It Break?
First Scenario: On your way home from work, a Prius cuts you off. The Prius driver then settles into the MPG-maximizing 55 MPH. Enraged, you pull up next to him and roll down your window. Looking for the nearest projectile, you reach for your iPhone 3G, then pause to ponder: Will It Break?
Second Scenario: You've gathered all the materials to build your secret lair, but don't have a hammer. Your MacGyver-like intellect puts together that your iPhone 3G—with it's tough glass case—should do the trick. You raise your 3G high overhead for that first swing, then stop and wonder: Will It Break?
Final Scenario: The apps in the App Store just don't entertain you anymore. So you decide to make your own: iBouncyBall. Holding your 3G above the pavement, you stop to ask yourself: Will It Break?
If you answered "No" to any of these questions, you'll most likely need a new display assembly, which includes the touchscreen glass, integrated digitizer, LCD, ear piece speaker, and home button. Apple has designed the assembly to work as a unit, so replacing individual parts is extremely difficult, and you'll probably want to replace the entire display assembly if any part of it breaks.
NOTE: This part will not work for the iPhone 3GS, but this one will.