Officially, FaceTime application is only available for iPhone 4 but folks iPhoneIslam introduced a tweak Facelt-3GS which allows users to enable FaceTime on iPhone 3GS, now they have updated Facelt-3GS to support iOS 4.2.1.
Users can grab updated Faceit-3GS via Cydia on jailbroken iPhone 3GS to enable FaceTime.
How To Enable FaceTime On iPhone 3GS
- Launch Cydia on your jailbroken iPhone 3GS
- Add the following repo: http://apps.iphoneislam.com
- Search for Faceit-3GS, install it and reboot your iPhone
- Go to Settings > Phone and simply turn ON FaceTime
You have successfully enabled FaceTime on jailbroken iPhone 3GS with Faceit-3GS.