You can view it on Github https://github.com/SamFleming/userCam
View the demo here http://samfleming.me/examples/userCam/
At the time of writing only Chrome 21+, Opera 12 and Opera Mobile 12+ support this (view browser support).
You can also stream the webcam to a canvas and access the raw data to create some really awesome effects. I'll make a blog post on how to do that using the plugin soon!
Checkout some of the other awesome demos out there, especially WebCam Toy.