From the official YouTube blog: "This new software is free for YouTube partners and allows you to produce and stream professional-looking live events directly to YouTube from your desktop.
It allows capture and switching between multiple video and audio sources, roll in of media files and images and add live effects and overlays.
If you’re enabled for livestreaming, you’ll see a link to download Wirecast for YouTube in your YouTube account."
More info: http://youtubecreator.blogspot.it/2012/04/celebrating-youtube-lives-first.html
Learn more about YouTube Live at: http://www.youtube.com/live