Excellent idea.
IMHO, this "wham thread" option accomodates both reader types.
Those among us who don't want to be spoilt by a warning can enjoy unbidden.
Those among us who prefer a warning can always check the thread before taking on a new story.
Just my thoughts,

Ankit
EDIT: Also, I think, if and when this policy is implemented, everyone should be informed via email or something one is bound to notice (if possible)...