Yahoo YHOO  co-founder Jerry Yang today resigned from the Internet company’s board of directors and all other positions at the company. He also resigned from the boards of Yahoo Japan and Alibaba Group.

In a statement, Yang said:

“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.”

The move is likely to be cheered by many of Yang’s detractors, who probably wish the rest of Yahoo’s board of directors followed suit. What it raises, however, is a giant question as to whether or not Yahoo might revisit the idea of being acquired either by a rival (Microsoft?) or by private equity investors.

Not only was Yang cited as the stick that muddied up Microsoft’s MSFT attempt to buy Yahoo in 2008, but he also recently told possible private equity suitors that neither he nor other Yahoo board members would support a takeover attempt — killing off possible deals with firms like Bain Capital, The Blackstone Group BX , Silver Lake Partners and TPG Capital.

Yahoo chairman Roy Bostock publicly reiterated the “not going private” position, but perhaps Yang’s departure could signal a softening. Again, all just speculation as the news is still very raw…

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