Cityfile today publishes a long post saying, essentially, that the ongoing rumor war between Anna Wintour and Conde Nast is the product of both sides using the media during tough contract negotiations. Let's look back:

These "Anna Wintour is leaving" rumors seem to pop up on a regular basis. They're quite standard contract negotiation tools. This, for example, from a 1999 Daily News story:

While Hurricane Floyd raged outside the Times Square headquarters of magazine empire Conde Nast yesterday, an even bigger storm appeared to be brewing inside.
One source said "it's all over the building" that Vogue editor in chief Anna Wintour will soon leave her powerful perch to become head of the Costume Institute at the Metropolitan Museum of Art.
One executive said Wintour's departure is expected "within the next six months."

The most recent rumor concerto built gradually:

[Pic via]