I successfully built Python 2.7.2, NumPy 1.61, and Scipy 0.9.0 in my home directory on a Centos5 system.  I am trying to build matplotlib 1.0.1 in my home directory, but I am having a problem with the GTK backends.  I also built pycairo 1.2.2, pygobject 2.14.2, and pygtk 2.10.6 in my home directory (using the libraries and headers installed in the default system locations).  I downloaded a few pygtk examples from the tutorial section of their web site and ran them to verify that pygtk works correctly.

Here is the error I get when I run a script that contains only the line "import matplotlib.pyplot":

python2.7 test.py --verbose-helpful
$HOME=/home/cfinch
CONFIGDIR=/home/cfinch/.matplotlib
matplotlib data path /home/cfinch/.local/lib/python2.7/site-packages/matplotlib/mpl-data
loaded rc file /home/cfinch/.local/lib/python2.7/site-packages/matplotlib/mpl-data/matplotlibrc
matplotlib version 1.0.1
verbose.level helpful
interactive is False
units is False
platform is linux2
Using fontManager instance from /home/cfinch/.matplotlib/fontList.cache
Traceback (most recent call last):
  File "test.py", line 1, in <module>
    import matplotlib.pyplot
  File "/home/cfinch/.local/lib/python2.7/site-packages/matplotlib/pyplot.py", line 95, in <module>
    new_figure_manager, draw_if_interactive, show = pylab_setup()
  File "/home/cfinch/.local/lib/python2.7/site-packages/matplotlib/backends/__init__.py", line 25, in pylab_setup
    globals(),locals(),[backend_name])
  File "/home/cfinch/.local/lib/python2.7/site-packages/matplotlib/backends/backend_gtkagg.py", line 10, in <module>
    from matplotlib.backends.backend_gtk import gtk, FigureManagerGTK, FigureCanvasGTK,\
  File "/home/cfinch/.local/lib/python2.7/site-packages/matplotlib/backends/backend_gtk.py", line 28, in <module>
    from matplotlib.backends.backend_gdk import RendererGDK, FigureCanvasGDK
  File "/home/cfinch/.local/lib/python2.7/site-packages/matplotlib/backends/backend_gdk.py", line 29, in <module>
    from matplotlib.backends._backend_gdk import pixbuf_get_pixels_array
ImportError: No module named _backend_gdk

Here is the beginning of my matplotlib build log, which shows that the build process is actually finding the GTK libraries:

basedirlist is: ['/home/cfinch']
============================================================================
BUILDING MATPLOTLIB
            matplotlib: 1.0.1
                python: 2.7.2 (default, Aug 30 2011, 12:57:00)  [GCC 4.1.2
                        20080704 (Red Hat 4.1.2-50)]
              platform: linux2

REQUIRED DEPENDENCIES
                 numpy: 1.6.1
             freetype2: 9.10.3
                        * WARNING: Could not find 'freetype2' headers in any
                        * of '/home/cfinch/include', '.',
                        * '/usr/include/freetype2'.

OPTIONAL BACKEND DEPENDENCIES
                libpng: 1.2.10
               Tkinter: no
                        * TKAgg requires Tkinter
              wxPython: no
                        * wxPython not found
                  Gtk+: gtk+: 2.10.4, glib: 2.12.3, pygtk: 2.10.6,
                        pygobject: 2.14.2
       Mac OS X native: no
                    Qt: no
                   Qt4: no
                 Cairo: 1.2.2

OPTIONAL DATE/TIMEZONE DEPENDENCIES
              datetime: present, version unknown
              dateutil: 1.5
                  pytz: 2010o

OPTIONAL USETEX DEPENDENCIES
                dvipng: 1.5
           ghostscript: 8.70
                 latex: 3.141592
               pdftops: 3.00
------------ SNIP -----------

There are no errors in the build or install logs, but I can post the rest of it if necessary.  Also, the library _backend_gdk.so is present in ~/lib/python2.7/site-packages/matplotlib/backends/.

Any suggestions would be appreciated!