Starting today, users of the newest wave of Roku devices will be able to access a real live YouTube channel. This long-awaited feature has been appearing through 3rd party services for some time - with Plex, for example - but has just appeared as an official channel on its own here on the 17th of December, 2013. Google itself set up this relative surprise of a release with little to no warning beforehand.
With a release of a feature as widely used as YouTube on a platform as relatively large as Roku, generally there's a leak or two to be had beforehand. What's appearing to happen this week is an instant release - aka Google did an excellent job of keeping this one under wraps. The app/channel is now available to Roku users, immediately if not soon.
This channel works with user subscriptions inside YouTube such as PTXOfficial and YouTube sign-in features like movies through Google Play. You'll be able to work with HD Streaming - that's 1080p, and you'll have the ability to work with "Send to TV" as well.
With Send to TV, users are able to sign in with a special code on whatever device they've got in their hands and the Roku YouTube channel. Once the two devices are connected, you can send (or "fling", if you prefer) YouTube videos from your device to your Roku. Generally this means you're looking at YouTube videos on your smartphone or laptop and you put them on a list that will then be played - wirelessly - on the Roku on your television.