Stream iOS camera live video to other device over Wifi
TJUNKS Video Camera

You can stream to other devices. This app does a lot, with video including uploading and sharing video on facebook, twitter etc but to stream video all the devices will need this app.

It also works across platform.

As far as personal experience goes I have only used it once to test it quickly, it workked accross a home WiFi network, other than curiosity I had no need for this.