A subtle feature in the "New Plan" ("New RCP" for ceiling plans) dialog proved quite confusing to new users. In 2009 it has changed. This is the one I'm referring to.
This is the dialog that appears when you choose View menu > New > Floor Plan. In the past all the levels of the project were displayed in the floor/ceiling plan views window. If you selected a level that already had a plan view associated with it and left the check in the box...no view, no message, no nothing. It just looked like Revit didn't do anything. It didn't...because the check box says, "do not duplicate existing views". A little cryptic.
Now when you look at the plan view window only the levels that don't have a view associated with them are displayed. When you uncheck the check box all the levels of the project are displayed. Much better, even though I was confused at first for the opposite reason, irony.