What's the cheapest possible way (including the hardware) to stream one to many, live, from a portable device, in an area that probably has public WiFi? Note this really needs a shoulder or helmet mounted webcam. It should be capable of 6-12 hours running on a battery and allow battery swapping to extend that.

I'm thinking Google+ Hangout + webcam + notebook in a backpack. I could be wrong, but I don't think any of the clever phones can use a separate cam.46-71 Trinity Rd, Ware, Hertfordshire SG12 7