Example: Turning on Labels
import arcpy
from arcpy import mapping
fc = r"c:\temp\fc.shp"
tempLayer = "tempLayer"
arcpy.MakeFeatureLayer_management(fc, tempLayer)
# Make the Layer Object
#
layer = mapping.Layer(tempLayer)
layer.showLabels = True
# Show the changes in ArcMap
#
arcpy.RefreshActiveView()
del layer
Enjoy