We route all media streams peer-to-peer. Which gives you the lowest possible latency and highest possible quality on a decent network connection. But, as other comments here have said, using a mesh topology has the downside of degrading badly if you have more than four (or so) participants in a call.
We'll add bridging in a future release, to support larger meetings, but it's actually fairly difficult to make a "routing media through the cloud in real time" architecture rock solid -- high quality and reliable for everyone, all the time. We've got customers in eight countries, so far, for example. So we'll need servers in multiple data centers, but somebody on an international call will always be farther from the bridge than is ideal.
We've surveyed a lot of people about video conferencing, and there's a lot of dissatisfaction with Hangouts and other similar products, much of which comes down to call quality, much of which is attributable to the difficulty of bouncing media streams through centralized servers.
We were in the most recent YC batch (W16) and a bunch of YC companies use our stuff. The basic idea is that big screens are super useful for team meetings, engineering standups, customer demos, etc. But big-screen video conferencing hardware has always been really expensive, or something you have to cobble together yourself. We're turnkey, set up in five minutes, are super easy to use, designed for getting real work done, and the hardware is free. You just pay $50/month per room, and there's no commitment (you can send us back the hardware and cancel any time).
You can try the Chrome browser version of our call stack from any laptop/desktop: https://pluot.co/new -- that bounces your browser to a new, unique, permanent meeting URL.
We've been following the Apple WebRTC development for a while, because we'd love to support Safari with no plugins, just like we can Chrome. We're hoping for full mobile WebKit support, too.