What does all this mean? The same functionality of the $35 HDMI Google Chromecast dongle can be replicated on a computer. $3 sure beats $35 if you want to experiment with this functionality.
The Cast icon shows up on Chrome devices if you are on the same network. I tried it with both computer, iOS, and Android devices. Unfortunately, Google half baked Chrome casting so it isn't available on the Samsung Chromebook.
Here is my Samsung 7" Galaxy Tab casting youtube to a Macbook Pro Retina. The Galaxy tablet is handing off the youtube to the Macbook.
It supports Google Play Music, Youtube and the SDK samples of Google Cast. I didn't try Netflix. I can't tell you how useful this except to say it can be done. Maybe I'll install it in my bedroom 27" iMac which is currently being unused. I still prefer Airplay any day of the week.
You can download and purchase it here. http://www.chromecatch.com/
Update: Apparently, you can do this for free with Leapcast. Maybe I'll install it on one of my Linux box with a follow-up.