This post is not a look at the technical specifications but rather on just how it works.
Firstly Facetime works right out of the box and there is no set-up needed. So if you want to start a video call with your friends, find your friend in your contacts list and just tap the Facetime button. If your all ready on a voice call and you want to shift to Facetime. Just tap the Facetime button on your screen.Once you do that an invitation pops up on your friends screen asking if they would like to join you in a video chat. If your pal clicks yes it starts working. You can also choose portrait and landscape mode.
The iPhone 4 has two cameras. One on the front above the display and one on the back next to the LED flash. The front camera has been tuned to be used for Video calling and must be held at arms length to present you in the best possible light.
During your Facetime call you can also use the back camera to share what you see.Tap a button and the phone switches to take back camera and you can share what your seeing right now. Tap a button again and it switches to the front camera. So if you on safari and a lion comes into view. Tap a button and the back camera comes on and you can share the live images with your friends. Allowing them to see what your seeing in real time.
The pic below is Apple's illustration on how this works. Talk with your friend and share your son blowing out the birthday candles in real-time.
[Image Courtesy Apple]
This is the official ad for the iPhone 4 Facetime