For the record I'd be keen to test your development efforts. I have a gig I'm hosting on the 26th of this month. You've got just over a week. GO!

HA most likely not until after blip NY at least.  but yeah, it'd be useful to bounce this off of people who have had experience running and streaming events.

Also, not sure if it was the computer or the program, but trying to use two firewire cameras crashed it. I've heard the USB cams are more stable with it, but have not vetted that info.

it doesn't have to be picture-in-picture, theoretically you can layout/composite the images any way you want, with as many webcams as your computer can allow. 

of course, when you have 2 webcams feeding 720p+ video data into a computer that's busy pushing out another HD stream in realtime, i would imagine this is all pretty taxing on the CPU.   my desktop machine seems to handle this acceptably, but i'm not sure how robustly your average entry-level laptop would deal with this.

time permitting, i'd love to develop this project further (implementing different layout schemes, realtime transitions, keyboard controls, adding overlays and messages, etc.) - i just need a solid chunk of a few afternoons to hash it out, as well as gaining a better understanding of common use cases (what features would be the most useful for chip events?). 

dave, let me know if you're interested in following this route. i'd be more motivated if there were people interested in trying it out and offering feedback.

At the most basic you'd be using several web cams into a laptop (with software mixing) which would then stream to ustream or similar. Beyond that you're options get almost limitless.