Just out from the Tribune:

Illinois House Speaker Michael Madigan today said impeachment proceedings will begin immediately against Gov. Rod Blagojevich with an inquiry into allegations that the governor used his office to try to sell the vacant U.S. Senate seat of Barack Obama. [...]

"It is my intention to appoint a special committee to begin immediately an investigation into the governor's conduct in office and to undertake the preparatory work that is a prerequisite to an impeachment proceeding in the Illinois House," Madigan said.

More specifics about the committee: Rep. Barbara Flynn Currie will chair it; Appellate Court Judge Alan Greiman will act as special counsel; the bipartisan membership will be made up of legislators with at least six terms under the belts; the committee plans to meet every day, with the exception of Christmas Eve, Christmas Day, New Years Eve, and New Years Day.

UPDATE: Here's some video via NBC5: