Example GeoNode local_settings.py file with STAMEN Basemaps

local_settings.py

# -*- coding: utf-8 -*-

from geonode import LOCAL_GEOSERVER

STAMEN_ATTR = ('Map tiles by <a href="http://stamen.com">Stamen Design</a>, <a'
               ' href="http://creativecommons.org/licenses/by/3.0">CC BY 3.0</'
               'a> &mdash; Map data &copy; <a href="http://www.openstreetmap.o'
               'rg/copyright">OpenStreetMap</a>')

MAP_BASELAYERS = [{
    "source": {"ptype": "gxp_olsource"},
    "type": "OpenLayers.Layer",
    "args": ["No background"],
    "visibility": False,
    "fixed": True,
    "group":"background"
}, {
    "source": {"ptype": "gxp_osmsource"},
    "type": "OpenLayers.Layer.OSM",
    "name": "mapnik",
    "visibility": True,
    "fixed": True,
    "group": "background"
}, {
    "source": {"ptype": "gxp_olsource"},
    "type": "OpenLayers.Layer.XYZ",
    "args": [
        'Stamen Toner',
        'http://stamen-tiles-a.a.ssl.fastly.net/toner/${z}/${x}/${y}.png',
        {
            'transitionEffect': 'resize',
            'attribution': '%s' % STAMEN_ATTR,
        }
    ],
    "visibility": False,
    "fixed": True,
    "group": "background"
}, {
    "source": {"ptype": "gxp_olsource"},
    "type": "OpenLayers.Layer.XYZ",
    "args": [
        'Stamen Toner Lite',
        'http://stamen-tiles-a.a.ssl.fastly.net/toner-lite/${z}/${x}/${y}.png',
        {
            'transitionEffect': 'resize',
            'attribution': '%s' % STAMEN_ATTR,
        }
    ],
    "visibility": False,
    "fixed": True,
    "group": "background"
}, {
    "source": {"ptype": "gxp_olsource"},
    "type": "OpenLayers.Layer.XYZ",
    "args": [
        'Stamen Watercolor',
        'http://stamen-tiles-a.a.ssl.fastly.net/watercolor/${z}/${x}/${y}.png',
        {
            'transitionEffect': 'resize',
            'attribution': '%s' % STAMEN_ATTR,
        }
    ],
    "visibility": False,
    "fixed": True,
    "group": "background"
}]

baselayers = MAP_BASELAYERS
MAP_BASELAYERS = [LOCAL_GEOSERVER]
MAP_BASELAYERS.extend(baselayers)

Pasted the above at the end of my local settings file (/etc/geonode/local_settings.py), and geonode crashed. I am running 2.4.

Added some documentation on the stackexchange question