Twitter CEO Resigns, Doesn't Tweet the NewsS

Ev Williams is resigning his post as CEO of Twitter after two years and handing the reins to chief operating officer — and Twitter board favorite — Dick Costolo, confirming reports of Williams' impending exit we first surfaced in July.

Williams insists in a blog post that this was all his idea — the hiring of Costolo and his own removal from the CEO job. He also said he's sticking around at the company, and remaining "completely focused on product strategy." Costolo, he said, is the man to handle the tricky work of growing the company quickly while maintaining its unique culture.

The challenges of growing an organization so quickly are numerous... I am most satisfied while pushing product direction.

In truth, we've been hearing, as we reported exclusively in July, that Twitter's board intentionally brought Costolo into duties once reserved for Williams amid concerns that the startup was not generating revenue quickly enough. Costolo, formerly CEO of FeedBurner, is said to be eager to take Twitter public — as the man in charge, not merely as CEO. (Incidentally, Costolo's first tweet as COO was a joke about his supposed ambitions: "Task #1: undermine CEO, consolidate power." Ha... ha?)

Twitter CEO Resigns, Doesn't Tweet the NewsS

That points to a Twitter IPO rather than a sale: Costolo sold FeedBurner to Google and by all accounts craves a stock offering, not another acquisition deal.

Williams, meanwhile, has been visibly stepping back from the business and growing his family. And some detractors have, for whatever reason, been gossiping about the co-founder's drinking, as we reported in July (and have continued to hear since). He'll certainly have more time for work life balance now and for, as he put it in his blog post, "building things." It seems unlikely that Williams, who invented Blogger before heading up Twitter, can confine his ambitions to 140 characters. Indeed, his resignation post weighs in at 396 words. And he has yet to tweet the news.

[Pics: Williams, top, and Costolo. Getty Images.]