I just watched this video and it was pretty good.
Explanation of the Shadow DOM and Web Components[youtube:https://www.youtube.com/watch?v=pQOuHNm5seY&feature=player_detailpage%5D
Here the link to the original post
Additional if you here are a few other resources Cantrell posted on his blog.
- What the Heck is Shadow DOM?
- Meet the Web Platform – Building on foundations (video)
- Web Components on Google+