Taken from http://www.nomansland.demon.co.uk/recentnews.html
"On the subject of SW collaborations, many people have asked if he is involved in the production of the new Opeth album Ghost Reveries. The answer is that unfortunately the PT touring schedule made it impossible this time around, but the band and SW hope to renew the ongoing collaboration with the next Opeth album. In the meantime the new album is as excellent as ever and needless to say highly recommended."
So yeah, it sounds like Opeth wanted SW to do this album, but he couldn't, and that they want him to do the next one maybe...
Just thought i'd let you know.
"On the subject of SW collaborations, many people have asked if he is involved in the production of the new Opeth album Ghost Reveries. The answer is that unfortunately the PT touring schedule made it impossible this time around, but the band and SW hope to renew the ongoing collaboration with the next Opeth album. In the meantime the new album is as excellent as ever and needless to say highly recommended."
So yeah, it sounds like Opeth wanted SW to do this album, but he couldn't, and that they want him to do the next one maybe...
Just thought i'd let you know.