I had to change my ticket. $40 to change it online, $50 if I call in. The online process was simple - look up reservation, check the "change" checkbox, accept all the warnings they pop up to alert you that, yes, you _are_ changing your ticket. No fuss whatsoever about locating a new flight, and there's always the large "No, nevermind" button at the bottom, so you know you can still go back...
Here's to hoping the rest of the system works as well.
Flight sunday morning, 1/13/07, IAD->JFK->ORD
Then bus (LEX) ORD->Urbana-Champaign.