Damn, I must admit I was sure that there was more info on him or his followers. A pity.
Thanks for the info though.
Lolth is portrayed (perhaps incorrectly) as the jailer of Tharizdun (or at least a contributing force). Her webs bind him, and her furthermore, her webs hold together the very fabric of reality against his assault.
I don't have the books at hand for the moment, but I believe the 4th edition preview books had details on him and the Dawn War.