T uesday's biggest news about the future of Microsoft is unquestionably the appointment of longtime company executive Satya Nadella as CEO, replacing Steve Ballmer. But the most intriguing aspect of the succession plan is the part about the guy who's signing up to be Nadella's technology adviser: Bill Gates. It's a new role for Microsoft's cofounder, who is turning over his chairmanship of the company to former Symantec CEO John Thompson.