Now that I've been away for a few hours and doing completely unrelated stuff I realized my mistake. I got the gameobject that holds "label" then got the object for "label" itself and try to change the text on that. However, that's a transform, not the script attached to the transform. When I get home (at work now) I'll figure out how to talk to the script attached to "label".
Might even be just
listEntry.GetComponent("label").GetComponent("UILabel").text="Yeahbaby!";
Though I think I remember something about using another command to retrieve script references.