Twitter has entered the programmatic realm with an ad retargeting feature called Tailored Audiences today. But with Black Friday and Cyber Monday in the rearview mirror, is it too late for holiday-minded retailers to fully take advantage of the better-aimed Promoted Tweets that are now available? After all, Fortune 500 brands formalized their yuletide marketing budgets weeks ago. Nathaniel Perez, global head of social experience at SapientNitro, doesn't think it's too late. "Twitter is very talented at releasing features that are incredibly simple to buy into," Perez said. &...