objectChecking.py

import pymel.core as pm

selected_material = pm.ls(selection=True)[0]

# Printing out the material type will give you the information you want to compare.
print selected_material.type()

# Here is a comparison check between the mental ray material and your target.
# selected_material.type() == 'mia_material_x'

# Below is a list to check through.
# Add the new material names you want to check.
material_types = ['mia_material_x']
# The in keyword will check through a list to fine if there is a match.
if selected_material.type() in material_types:
    print 'Whoo Hoo.  We got a mental ray material'

# You can push this further by comparing class types and using the is keyword instead.
# This will allow you to directly compare instances instead of strings.