If you look over at PODCAST he has come up with some excellent speculation based on the latest patch notes with regards to the Red Plague here is the snippet below:
The rumors started first. Sickness. Deaths. Before long the rumors weren't just whispers but screams echoing into darkness - The red plague had come.
In response to the virulent outbreak, merchants have abandoned their routes, preferring instead to remain in the perceived safety of larger cities. The Crafting and Training Guilds have issued a decree recalling all guild members to their respective capitals rather than risk the loss of their master crafters and trainers. For the first time since the war began, experienced Order and Destruction forces must now head to Altdorf and the Inevitable City in order to consult with career trainers, craft masters, and merchant kings - for until a cure is found no sane man will travel the battlefields of the land alone.
Yitu (the link is wrapped in the google translator)an excellent german blog has been following these rumours for some time.
I would love to see the Skaven make an appearance as a playable race in War. After reading Skavenslayer (A Gotrek & Felix novel) which I would fully recommend. I came to like the race which almost seem have to even more character than those lovable green skins. Not to spoil the book but the Skaven use plague to weaken their foes before they surface. Wouldn't it be cool for Mythic to use the same tactics.