When Sheryl Sandberg, the COO of Facebook, wrote Lean In, she did not want the book to be just a book, or just another celebration of the world's top-achieving C-suite women.

"I wanted the book about the community," says Sandberg. Her goal was to form circles of professional women around the globe who would support, mentor and help each other.

While no one doubts her personal influence in the arenas of gender equality, and her own influence as a role model, the impact of the working circles, has surprised many observers.