From the YouTube blog:
Warner Music Comes Back to YouTube
Music Licensing: It's complicated. Let's face it. But today all of that is beside the point: we are happy to announce that Warner Music Group (WMG)'s artists are returning home to YouTube. Under this new, multi-year global agreement, you will be able to discover, watch and share Warner music on the site. The partnership covers the full Warner catalog and includes user-generated content containing WMG acts.
With Warner on board, we now have artists from all four of the major music labels & publishers together with hundreds of indie labels and publishers on our platform. Warner will also be able to sell their own ad inventory and will...
use our Content ID technology to claim and monetize user-generated videos uploaded to YouTube by Warner Music fans. The partnership is based on a revenue share generated from the ads on the videos, and this makes good business sense for everyone involved: artists and labels can make money from their videos and the YouTube community gets to enjoy them.But enough talk... let's get back to the rock. Warner's videos will begin appearing on YouTube in the near future.