Thank goodness. Here’s his letter (pdf). He’s out as of about an hour ago. The Senate President’s statement:
In deference to the need for public trust on matters before this great institution, Jim Marzilli has made the right decision for the Massachusetts Senate, the citizens of the Commonwealth, and himself. While the Senate deals with the conduct of another member, Jim Marzilli’s resignation will begin the process of restoring the public’s trust in their government. As we have stated previously in our strongest voice, Dianne Wilkerson should follow this example and resign immediately.