Planescape: Torment - Who owns the rights?

Blue's has picked up on a tweet from Direct2Drive, saying they'd love to re-release Planescape: Torment if they could only figure out who controls the rights:

@Daggity hah, would love to re-release Plancescape...if we could find someone who actually owns the rights! Sad.

Presumably they would have already started with Interplay and WotC?