Steve Jobs, the visionary who remade Apple into the world’s dominant maker of tech gadgets, has resigned as the company’s CEO.

In a letter to the Apple Board of Directors and “the Apple Community” Wednesday, Jobs wrote that Chief Operating Officer Tim Cook will take over his CEO duties.

“I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple’s CEO, I would be the first to let you know. Unfortunately, that day has come. I hereby resign as CEO of Apple. I would like to serve, if the Board sees fit, as Chairman of the Board, director and Apple employee,” Jobs wrote.

I is unclear from this initial report when the resignation is effective, but from the tone of the memo, it sounds as though it may be immediately.