Microsoft has announced that they are working with Universal Pictures to release HD DVD titles using VC-1 and iHD. Here's part of their press release:
Today at the National Association of Broadcasters convention, NAB2006, Microsoft Corp. (Nasdaq: MSFT - News) and Universal Pictures announced their collaboration on the release of next-generation HD DVD discs using VC-1, the video compression standard recently approved by the Society of Motion Picture and Television Engineers (SMPTE) and one of the mandatory codecs in the HD DVD specification. Universal will also use iHD for the interactive features of the new titles. The launch of HD DVD players and titles last week in the U.S. represents the first broad market availability of high-definition optical media for consumers.

As part of Universal's initiative to provide new digital entertainment experiences for consumers using the best solutions available, the studio is using VC-1 for its initial HD DVD titles, including "Serenity," "Doom," "Apollo 13," "The Bourne Supremacy," "U-571," "Van Helsing" and many more. Given the lower bitrate required with VC-1 to deliver pristine 1080p, high-definition movies, Universal will have room to spare within HD DVD's 30GB capacity for interactive features and other extras. With iHD, the studio is offering interactive menus that are overlaid on top of the movie and accessible without interrupting playback. Additional features, such as user-defined bookmarks that stay with the title, picture-in-picture commentaries, and network access to download new features and HD movies trailers, all access standard HD DVD features (secondary video decoder, network access and persistent storage).
The press release also mentions that all HD-DVD titles from other US studios are using the VC-1 codec as well. More information can be found here.