This brings us to Southwest Airlines (NYSE: LUV), the poster child for competitive advantages. Southwest's chief executive and founder, Herb Kelleher, announced his succession plan yesterday. Investors have anxiously awaited this news since Kelleher's prostate cancer diagnosis two years ago. On the conference call yesterday, Kelleher said he had struck a deal with the board of directors under which he had promised to name a successor on his 70th birthday or when he started drooling uncontrollably. His 70th birthday came March 12.