Martin Nisenholtz, one of the most respected executives in the online media world, is leaving the New York Times, where he has been senior vice president of digital operations for quite awhile and has helped oversee the news company’s digital efforts in a number of directions — including mobile platforms like the iPad (s aapl) and the paper’s introduction of a metered pay wall for its website.

… was named senior vice president, digital operations for The New York Times Company in February 2005. He is responsible for the strategy development, operations and management of The New York Times Company’s digital properties. Mr. Nisenholtz was chief executive officer of New York Times Digital from 1999 to 2005. Previously, he was president of The New York Times Electronic Media Company from 1995 to 1999. In that role, he was the founding leader at NYTimes.com. [The New York Times Company Bio]

As a young media-industry entrepreneur, I have had a chance to interact and learn from Nisenholtz. He was generous with his time and advice, and I am looking forward to whatever he does next. The NYT’s media blog has a short post on his departure with quotes from an internal memo about his contributions to the paper’s digital initiatives, and Dave Winer has a note about how key Nisenholtz was to the development of the RSS standard.