I have a custom list which can contain a CustomContentType. This is how i create a new item:
//Create root folder
SPListItem rootItem = navigation.Items.Add();
SPContentType folderType = navigation.ContentTypes["ListLevel"];
rootItem[SPBuiltInFieldId.Title] = "root";
rootItem["ContentTypeId"] = folderType.Id;
rootItem.Update();
The problem is, when I'm looking at my list after this I see that:
When I go to the list via a webbrowser and create the content type manually, everthing is fine. (Which means that the Title is "root" and not the ID).