And, in a letter to staff at the company he helped create in 1976, he recommended chief operating officer Tim Cook to be his successor. Cook was actually on the short list since Jobs took medical leave in January. He's been running day-to-day operations at Apple for 13 years. It looks like the company heeded Jobs' advice, since it announced in a press release issued today that Cook will be taking Jobs' place in the executive office. Jobs, meanwhile, will serve as chairman of the board while he battles cancer and other undisclosed ailments. This afternoon tech analysts were all a-Twitter, opining about Jobs' resignation and legacy. Merc columnist Chris O'Brien contends that the Apple titan "reshaped Silicon Valley in his own image." Many call it a tectonic shift, but also admit they knew this day was coming.