Previous releases of Revit offered a check box to decide if we wanted a tag to show up as we placed various elements. For example placing a door offered us this on the Options Bar.
With 2011 this has been changed a little. There is a button to press to choose tagging or not. Fun to see the puzzled look trying to work out where the option went. It goes something like, "I could have sworn there was a way to stop tagging when I place families?!? Oh!! There it is!!".