Iain - I don't actually think the arrow-keys work for nudging in RDS; at least they don't work for it in RayDream 3D, and there's not that much difference in the GUI's. Trying to use them to nudge objects results in unpredicted movements that are frustrating to understand. That may be why these RDS folks haven't used the feature before. You might want to send a note off to MetaCreations asking for the feature to be included in later versions of Carrara. (I'd be grateful if the feature were there when I upgrade....)