FaceTime is a proprietary video calling product. it has been developped by Apple
Facetime hacked ?
Concerning Hacking, see the Apple Answer :
“Your Apple Device CANNOT be hacked BUT if you jailbreak, open mysterious mails from unknown people, download files etc. that is not verified by Apple, you have a chance to get hacked and if you jailbreak, your apple device is no longer an apple device.”
Sources : discussions.apple.com