As announced, Google opened the VP8 codec to the open source community as the WebM Project.
WebM defines the file container structure, video and audio formats. WebM files consist of video streams compressed with the VP8 video codec and audio streams compressed with the Vorbis audio codec. The WebM file structure is based on the Matroska container. The full source code is freely donwloadable.
Just yesterday the x264 community released his personal technical opinion on the VP8 codec in this blog post.