Google just announced this today and it looks awesome. Basically, this plugs into your TV and you are able to stream video directly to your TV from major sites like Youtube, Netflix, and Pandora. What makes it different is that, from Android or iOS apps or from Chrome, instead of playing the media directly on your device, you can tell it to send it to your Chromecast device. This will cause the media to start streaming on your TV right away. You can then close that app down and it will continue playing.
Sources for media are limited right now (because it was just released), but I expect that many apps will be doing this very soon. I would have to imagine that WatchESPN will jump on this and I don't see any reason that BTN wouldn't do this as well. Looking at the SDK, it seems like it is straight forward to implement this, so I would think that someone will have a server that streams over the local network soon enough so you can watch all of those torrented Michigan classics on your TV.
The best part is that it is $35. Right now, it also comes with 3 months of Netflix for free, even if you already have an account. That, essentially, makes this an $11 toy that has huge potential. I just bought one, but I thought I'd pass this along to other techies on here who might be interested in it.