Gonzales out, now what?

Attorney General Gonzales has resigned.  ABC News: Attorney General Gonzales Resigns  Will his resignation take effect only upon confirmation of his replacement?  The rumor has been that Homeland Security Secretary Mike Chertoff will be nominated to replace Gonzales, but not clear if this is a done deal.  Chertoff is well-respected and likely would be confirmed, but he will face a lot of his questions regarding his prior tenure as head of the criminal division at DOJ.  During his nomination for DHS Secretary, Chertoff was asked about his role in Administration policies on military tribunals, foreign detainees, torture and use of the material witness statute, among other things.  One can expect renewed questioning on these subjects.  He will also be grilled about his tenure at DHS, particularly his response to Katrina (from Senate Democrats) and illegal immigration (from Senate Republicans).