Unfortunately, my experience is mostly with live stage performances, so distance hasn't been a factor. And I prefer cables when I can use them, because it's cheap. I've used a couple of programs for video manipulation. One that might work (but is a little weird if you aren't used to it) is Isadora. Here's a thread on their forum about using an iPhone to stream:http://forum.troikatronix.com/forum/Isadora_C2/Communication_%26_Sensors_F6/stream_live_video_with_iphone_4s_P13314/
The mobiola app looks interesting.
Are you using multiple projectors or just one? I'll ping the VJs I know and see if any have dealt with this.
Another route to consider is something like this:http://homestore.cisco.com/en-us/cameras/linksys-WVC80N_stcVVproductId84737621VVviewprod.htm
You'd need a wifi hookup, though. Would this be something that USI Wireless might be interested in sponsoring? Might be worth a shot.