Why did Scott Moore really leave Yahoo?The departure of Scott Moore, head of Yahoo's Media Group, seemed hasty. Microsoft exec Jeff Dossett, in talks with Yahoo for an entirely different job, ended up replacing Moore. And in an interview with the Wall Street Journal, Moore only gave the vaguest of hints as to what he'd do next — which suggests he hadn't really had time to think it through. But a tipster suggests why Moore might be leaving now: Retention bonuses, issued to top execs after Microsoft's takeover offer, are kicking in.