Guys,
I found this news at IGN.com:

Warner Bros. Supports UMD
Batman Begins, Matrix trilogy coming soon.
by Juan Castro
October 7, 2005 - While many major studios have decided to release movies on Sony's new UMD format, some studios have been reluctant to follow suit. Dreamworks Home Entertainment and Warner Bros. Home Video are perhaps the two biggest studios that have yet to release any movies on UMD. Well, it looks as though that's going to change. According to a recent announcement, Warner Bros. is preparing to release a slew of titles in coming weeks.


And it seems as though Warner Bros. wants to make up for lost time. As part of the studio's first batch of UMD releases, it plans on shipping all three Harry Potter films, the Matrix trilogy, Batman Begins, The Island, Polar Express and Constantine. Currently, there's no word whether any of these movies will include bonus features of any kind, apart from Japanese and English subtitles and audio. Now that Warner Bros. has decided to support the UMD format, there's a good chance the studio will begin transferring a backlog of DVD releases over to UMD.
Look for the first batch of Warner Bros. movies to hit store shelves late November.

Until then, stay tuned for any further developments.