Does the iTunes that streams to the ATV's have to be on a computer or can also the iOS iTunes suffice? Providing you have the content on a hard drive and not on the iOS device.
content on the iOS device can be AirPlayed to the AppleTV.
Content on a Hard Drive - you would probably use the Apple Remote App on the iOS device to control the Apple TV or the computer running iTunes. YOu still need a computer running iTunes for this.
There are some apps that would allow streaming from a NAS or other network share. Some of these support AirPlay. I've never found one that works well for Video, but Audio usually works well.