Google is almost finalized with the VP9 codec, the successor to the increasingly-used VP8 codec.
Shared today on the WebM blog
is that the VP9 bitstream will be frozen on 17 June and following that VP9 will be enabled by default in Google's Chrome web-browser and Chrome OS operating system. Once that support lands, YouTube plans to begin supporting the VP9 codec too.
Right now VP9 can be checked out from an experimental branch of the libvpx code-base. Like VP8, the next-generation VP9 codec will be open-source and free for use by all parties.