Keen! I'm a fan. I like the idea of Ravenloft's domains being in the Shadowfell. Significantly unnatural, but close enough to the mortal world to allow accidental mist-slippage.
Though this does mean that 4e's treatment of Ravenloft is likely to be "side-quest" oriented and not "campaign setting" oriented, I'm pretty okay with that.
Yay! This bodes very well for the book, very well indeed.