Here's an article summary from the Harvard Business Review (October 2010):
Why Succession Shouldn’t be a Horse Race (Anne Mulcahy, pp. 47-50). The former CEO at Xerox, Anne Mulcahy discovered Ursula Burns nearly a decade before Burns succeeded Mulcahy in the first woman-to-woman CEO succession at a Fortune 500. The big difference between the Xerox succession scenario and the one at GE when Jack Welch left might demonstrate the difference between men and women: Collaboration vs. Competition. Welch set up a three way competition. The result was turbulence, and the two losers left GE. The Mulcahy-Burns succession was more thoughtful and resulted in a much smoother ride.