Yahoos! at the gates
To rephrase a point that Bill Walsh makes with characteristic effectiveness in The Elephants of Style ("Punctuation is not decoration," pp. 36-37), the obligation to mark a proper name is not an obligation to reproduce a trademark. This hed isn't reporting, it's cheerleading -- if not for the company itself, for its graciousness in sending an expert north to enlighten the hayseeds.
Yahoo is a company. Yahoo! is a severe case of misplaced terminal punctuation that should be restricted to the ad columns with an armed guard at the border. Don't get the two confused.