http://blender.stackexchange.com/q/34540

blender-append-known-obj-from-another-file.py

import bpy

# current scene
scn = bpy.context.scene

# path to the blend
filepath = "/path/to/file.blend"

# name of object to import
obj_name = "Cube"

# append, set to true to keep the link to the original file
link = False

# link all objects starting with 'A'
with bpy.data.libraries.load(filepath, link=link) as (data_from, data_to):
    # find all objects named "Cube"
    data_to.objects = [name for name in data_from.objects if name.startswith(obj_name)]

#link object to current scene
for obj in data_to.objects:
    if obj is not None:
        scn.objects.link(obj)