If you read the details of this thing all it really is is a wifi connection that forwards an HDMI signal to your TV. They've just abstracted a software layer that Google can control to channel you through their portal. It lets them set a standard that other companies have to abide by if they want their content accessible from Google's device. They package it to make it easy for the consumer, but it's really just an example of Apple style content control.
Seriously. You can do the same thing with any laptop/desktop/phone/tablet with an HDMI-out port, and without needing a proprietary device!