Most Powerful Women: The network effect by Patricia Sellers @FortuneMagazine October 25, 2011, 9:25 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons What happens when influential women like Meg Whitman, Ellen Kullman – and a guy: Warren Buffett – get together? They share smart ideas and – forge unexpected new relationships. FORTUNE — Big topics — the global economy, presidential politics, boardroom drama — got plenty of airtime at Fortune’s annual Most Powerful Women Summit in early October. Meg Whitman (No. 9), the new CEO of Hewlett-Packard HPQ , outlined plans for calming the waters at the tech giant. Warren Buffett — the lone male interviewee — discussed the European crisis and the “Buffett Rule” to increase taxes paid by the rich. (“It’s a boyhood dream,” he quipped. “I wanted to have a tax named after me.”) But the spirit of the summit — women offering advice and making connections — emerged in smaller, spontaneous moments: IBM IBM senior VP Ginni Rometty (No. 7) confided that “growth and comfort do not co-exist.” Lululemon LULU CEO Christine Day and Google GOOG VP Marissa Mayer (No. 38) bonded while chatting about their companies’ approaches to innovation. And when Gloria Steinem walked on stage for her first-ever appearance at a Fortune event, some 400 accomplished women greeted her with an appreciative standing ovation. Photographs by Robyn Twomey This article is from the November 7, 2011 issue of Fortune.