As a result of the resignation, we know a lot more about the campaign financing case being built by the U.S. Justice Department against Jesse Jackson Jr., starting with the first official confirmation from Jackson that it is under way.
While we're told that charges are not imminent, there is wide speculation that a plea deal is not far off.
The 2nd District congressman known informally as "JJJ" spoke in far more formal terms in his resignation letter, language frequently heard in plea agreements with federal prosecutors.
Jackson wrote, "I am doing my best to address this situation responsibly, cooperate with the investigators, and accept responsibility for my mistakes, for they are my mistakes and mine alone."
Acceptance of responsibility is something that judges look for when sentencing criminal defendants who have pleaded guilty.
Jackson lawyer and former U.S. Attorney Dan Webb says, "Mr. Jackson is cooperating with the investigation. We hope to negotiate a fair resolution of the matter but the process could take several months."
If he becomes a felon, Jackson's federal pension might be curtailed by legislation sponsored by Illinois Senator Mark Kirk.
For now, though, the National Taxpayers Union estimates that taxpayers spend more than $800,000 annually on the pensions of corrupt former members of Congress. These disgraced notable congressmen all received annual pensions despite being convicted of corruption.
Based on the written remarks from Jackson's attorneys, and information federal law enforcement sources, it appears that both sides are interested in wrapping this up without a trial.