Chairman and CEO, AT&TRank: 21Why he matters: Stephenson hopes to transform a company rooted in yesterday's technology -- telephone landlines -- into a multiplatform provider of telecom services. AT&T's decision to rebrand the Cingular network with Ma Bell's 122-year-old moniker got a big boost with the news that AT&T would become the exclusive carrier of Apple's iPhone.
But Stephenson must also find success with the U-verse -- a long-delayed IP-based television system that will put AT&T in direct competition with cable companies. In May, AT&T announced that it will spend $6.5 billion ($1.4 billion more than previously announced) to roll out the system in 20 cities. If the effort fails, Stephenson could go the way of the rotary dial.
Meet 50 Who Matter winner Gina Bianchini. Her site, Ning, lets anyone be a social networking mogul. (more) 
