There has been a lot of inquiry about recent events. This post is meant to clear that up and avoid speculation. In particular, I am posting this as a follow-up to a comment I had made previously.
This is also a logical follow-up content in the following:
Recently, largely due to poor inter-moderator communication, Bill and Qiaochu got into a disagreement that led to both temporarily (for one week) losing their moderator abilities.
During this time, Bill officially and permanently resigned as a moderator via direct communication with the SE team, making his loss of moderator abilities permanent. I regret to inform you that Bill D. is no longer a moderator of MSE. But Qiaochu will return to moderator-ship within a week.
There also is a lot of speculation about Bill's current suspension. It would be a breach of privacy to describe the details of any action leading to suspension, but his suspension was independent of Bill's resignation. He changed his name, and wrote several messages indicating that he was planning on leaving the site entirely. I might also note that another user was suspended at the same time for largely the same reason. Due to Bill's unnaturally well-known suspension history (and the original question), I will comment that the length of the suspension follows SE Guidelines.
As a moderator, allow me to say that I have confidence in our moderator team and in the invaluable support of the official SE team (who have been with us throughout), and we continue to live and learn as individual moderators and as a team. As a member of the community, allow me to say that it is always sad to see a high contributor decide that he no longer wants to be a part of the community. Many of Bill's answers had very clear exposition. But I also have confidence in this community and the incredible speed with which it answers and addresses all sorts of mathematical concerns.
On the other hand, I am very happy to announce that I have been told that Zev will be returning to the site very soon as well.