Can the Macbook's webcam be ON without LED indication? Was reading some topics online about hackers accessing user's webcams (on Windows) to spy on them etc, and I am now interested to know if I'm at any risk. 

To make it simple, these are my questions :


Can Safari allow websites to activate the webcam without my permission ?  
Can the webcam be activated without the LED being lit ? 
Are there any known trojans that affect macs and leave them vulnerable for such hacks ?


Thanks
This research paper reported by the Washington Post and Ars Technica says yes. 

Though it was only tested on "old" Macs (Late PPC, early Intel)