IPhone :: Can I Use As A Webcam For Mac?

This would be a cool feature, as there is some software out there that lets you use like cannon cameras a webcams, so u can display what the cameras filming on the computer screen. I tried that software and many other software with my iphone and it doesnt work. does anybody know any software and cydia package that will allow me to do this? i asked someone at the apple store before my phone was jailbroken and they said "no, but theres probably a jailbreak app for it". and i was like "wtf?" you work for apple, your supposed to be against this and your telling me how i can benefit from it. ok but that was just something i wanted to say. but any help at all is appreciated.