So I went and looked for news. I found that an NBC Chicago blog reported on January 28, 2011:
Rezko is serving his time at a county jail in Wisconsin.
His lawyer said today that no matter the outcome of his ongoing efforts to obtain a new trial, Rezko remains prepared to testify against Blagojevich at his own retrial in April.
Judge St. Eve set Rezko’s sentencing for October 21.
So, just in case Rezko's sentencing actually happens eight months from now, he will by then have served 39 months in an undisclosed facility between conviction and sentencing. That seems pretty odd.