As Jack Dorsey unexpectedly came back to Twitter to take the product lead, serving as Executive Chairman, it quickly became clear that Evan Williams had his mind elsewhere.

Williams made a post on his personal blog this evening, discussing his plans in no great detail. The plans do, however, include staying at Twitter as a board member. Willimas wrote:

After stepping down from CEO six months ago, my mind started to wander. The reason I left Blogger/Google when I did is that I felt it had reached a place where it was on solid ground and in capable hands (at the time, Jason Goldman’s as product manager). Though still an independent company, I realized Twitter may be at a similar point today. So, as was reported in various places yesterday, I’ve decided to scale back my role at the company. (I’m still involved, but it’s no longer my full-time job.)

I’m not ready to talk about what I have planned next, but I will venture a prediction about what’s next for Twitter: It will be bigger and better.

…

First of all, I’m not disappearing from Twitter. I remain on the board of directors and will frequently meet with many folks there to help in any way I can.

However, now that Twitter is in capable hands that aren’t mine, it’s time to pick up a whiteboard marker and think fresh. There are other problems/opportunities in the world that need attention, and there are other individuals I’d love to get the opportunity to work with and learn from. (Details to come.)

Jack Dorsey is appearing along with co-founder Biz Stone on CNN’s Piers Morgan tonight. More on that to come. Here’s what Dorsey talked about at Columbia University.