Deadwing is indeed available in both:
A "special edition" DVD-V that comes with a 72 page hardback book package, and includes both the CD and DVD-V 5.1 surround sound version. But this doesn't include any of the bonus material or features included on the separately released "DTS" DVD-A edition.
The DVD-A edition imho is vastly superior having PCM stereo 24/48k, DTS 5.1 24/48k and DVD-A 24/48k, but most importantly has 5.1 versions of "Revenant", "Mother & Child Divided" and "Half-light"
The DVD-A is worth the money just to get "Half-light" which was the B side of the Lazarus single and imho is the best song Steven Wilson has ever written and doesn't appear on any other studio album (it's on Atlanta and Anesthetize)
http://www.youtube.com/watch?v=1XdTvfH8FWY
The 5.1 version is just chilling.
Definitely agree that the DVD-A is superior - the DVD-V special edition was pretty much an impulse buy when I was at a show in Boston. When I saw that it was signed by each band member, that was the clincher.