Forstall, a senior vice president in charge of Apple's mobile operating system, iOS, will act as an adviser to CEO Tim Cook until departing some time next year, according to a news release from the company. As the man behind the system that ran Apple's industry-changing iPhone and iPad, Forstall had beenconsidered a favorite to replace Jobs as CEO after Jobs' death last October. More recently, Apple observers pegged Forstall, 43, as the next in line behind Cook. Along with marketing chiefPhil Schiller and design guru Jonathan Ive, Forstallanchored the company's top tier of executives, frequently speaking at Apple's heralded product unveilings to showcase the ins and outs of operating-system upgrades. Many felt he was the most logical choice to continue Jobs' legacy of innovation at Apple, where 70% of revenue now comes from the mobile devices that iOSpowers. "He was as close to Steve asanybody at the company," Andy Miller, former head of Apple's iAd group, told Businessweek last year."When he says stuff, people listen." The Apple press release did not say what Forstall plans to do when he leavesthe company. Apple did not immediately respond to a message seeking further details