One of the things that Apple brought back to the Mac from iOS devices is FaceTime. The video calling feature on iPhone 4 and fourth generation iPod touch now works on the Mac using a downloadable FaceTime application.
Having FaceTime on the Mac surely will increase adoption of the proposed open standard video calling feature. To activate FaceTime on the Mac, you only need an Apple ID which can be the same as the one on your iOS device. Using the same ID will prompt all devices to alert you at the same time and you can choose to respond on the device of your choice.
However using the same ID will prevent you from making a FaceTime call to yourself between your devices. On the Mac however, there is an option to use multiple emails in case such situation is required.
To avoid impractical situations, Apple has apparently implemented push notification into FaceTime for Mac. This means when someone makes a FaceTime call to your email, the Mac will alert you even when the app is not running.
As FaceTime uses a system process to monitor for incoming calls, should you choose to uninstall the application, you’ll need to sign out of the app before you can remove it. Otherwise you’ll see a notice saying the app is still in use.
To stop FaceTime from receiving calls, turn FaceTime off in the app’s Preferences.