Yahoo just announced that co-founder and former CEO Jerry Yang has resigned from the company’s Board of Directors and all other positions with the company, effective today. That includes resignation from the Boards of Yahoo Japan and Alibaba.

Yang wrote in a letter to the Yahoo Board Chairman Roy Bostock, “My time at Yahoo!, from its founding to the present, has encompassed some of the most exciting and rewarding experiences of my life. However, the time has come for me to pursue other interests outside of Yahoo! As I leave the company I co-founded nearly 17 years ago, I am enthusiastic about the appointment of Scott Thompson as Chief Executive Officer and his ability, along with the entire Yahoo! leadership team, to guide Yahoo! into an exciting and successful future.”

“Jerry Yang is a visionary and a pioneer, who has contributed enormously to Yahoo! during his many years of service,” said Bostock. “It has been a pleasure to work with Jerry. His unique strategic insights have been invaluable. He has always remained focused on the best interests of Yahoo!’s stakeholders, including shareholders, employees and more than 700 million users. And while I and the entire Board respect his decision, we will miss his remarkable perspective, vision and wise counsel. On behalf of the Board, we thank Jerry and wish him all the very best in his future endeavors.”

“We appreciate Jerry’s comments and share his enthusiasm for the company’s prospects,” he added. “With Scott Thompson leading an outstanding team of Yahoos to deliver innovative products and an engaging customer experience, Yahoo!’s future is bright.”

Thompson himself said: “I am grateful for the warm welcome and support Jerry provided me during my early days here. Jerry leaves behind a legacy of innovation and customer focus for this iconic brand, having shaped our culture by fostering a spirit of innovation that began 17 years ago and continues to grow even stronger today. Jerry has great confidence in the future of Yahoo!, and I share his confidence in the enormous potential of Yahoo! in the days ahead.”

While the search was on for Carol Bartz’s replacement (fired last year), it was rumored that Yang was really running things, despite Timothy Morse being appointed interim CEO.

Yang co-founded Yahoo in 1995 with David Filo and served as a member of the Board of Directors since March 1995. His time as CEO lasted from June 2007 to January 2009.