OK, that got me a hair further  :-)  With your suggestion I got past that speed bump by:
sudo apt-get install tk8.5-dev tcl8.5-dev

Now the error is a little more sinister.  I did a tiny bit of research and some posts says the error could be due to no installation of g++.  but...
sudo apt-get install g++
Reading package lists... Done
Building dependency tree
Reading state information... Done
g++ is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
building 'matplotlib.backends._tkagg' extension                                                                              
g++ -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions build/temp.linux-i686-2.6/src/agg_py_transforms.o build/temp.linux-i686-2.6/src/_tkagg.o build/temp.linux-i686-2.6/CXX/cxx_extensions.o build/temp.linux-i686-2.6/CXX/IndirectPythonInterface.o build/temp.linux-i686-2.6/CXX/cxxsupport.o build/temp.linux-i686-2.6/CXX/cxxextensions.o -L/usr/local/lib -L/usr/local/lib -ltk8.5 -ltcl8.5 -lstdc++ -lm -lfreetype -lz -lstdc++ -lm -o build/lib.linux-i686-2.6/matplotlib/backends/_tkagg.so                   
building 'matplotlib.backends._macosx' extension                                                                             
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -DPY_ARRAY_UNIQUE_SYMBOL=MPL_ARRAY_API -I/usr/lib/python2.6/dist-packages/numpy/core/include -I/usr/local/include -I/usr/include -I. -I/usr/lib/python2.6/dist-packages/numpy/core/include -Isrc -Iagg24/include -I. -I/usr/include/python2.6 -c src/_macosx.m -o build/temp.linux-i686-2.6/src/_macosx.o                                                                                                                    
gcc: error trying to exec 'cc1obj': execvp: No such file or directory                                                        
error: command 'gcc' failed with exit status 1

Is it possible I need a special version of g++?