It's worth noting that while this is becoming available in chrome now, the WebRTC APIs that both Chrome and Firefox are working on (and will likely start showing up in the 3-6 month time frame) is also likely to provide p2p message passing support.
There's a group of people beginning work on porting some of the traditional p2p constructs like DHTs into the browser, for those interested: http://joincollage.com/webp2p
> the WebRTC APIs that both Chrome and Firefox are working on (and will likely start showing up in the 3-6 month time frame) is also likely to provide p2p message passing support.
And most importantly, the WebRTC APIs will be standardized and available on the web, not just for browser extensions.
There's a group of people beginning work on porting some of the traditional p2p constructs like DHTs into the browser, for those interested: http://joincollage.com/webp2p