I was doing similar research recently and found a working demo: http://gadgets-code.com/taking-webcam-photo-with-opera-browser-new-technology
It requires install of an experimental version of Opera: http://snapshot.opera.com/labs/camera-and-pages/
Happy hacking!
UPDATE [20 May 2012]:
http://www.webrtc.org/running-the-demos - WebRTC - GoogleChromeCanary - about://flags - enableMediaStream + PeerConnection :) Me recommends - Jerome Etienne's blog - http://learningthreejs.com/
UPDATE [13 Sep 2012]:
WebRTC enabled in Chrome 21 by default (change introduced couple weeks ago)
UPDATE [2 Jul 2014]:
WebRTC is mainstream / huge: http://youtu.be/GBAEG_RuqeE?t=50m1s (Google Hangouts, Amazon Mayday, Snapchat)