In certain zoom I see many city labels "written" on each other. I know there is a feature that set to auto hide labels that override each other ( and I'm not talking about rendering from specific scale...) Where can I find it in QGIS?
Today (in 1.8), you have two choices of labelling:
Old one, inside the properties menu of the layer
New one, in the icon toolbox.
The new one has collision detection, while the old one will be removed with the next QGIS version. So you better switch over to the new one.