Under Debian/Lenny/i486, I install python3.0rc3.
After untar the Python3.0rc3 package, I replace in the configure
"/usr/local" by "/usr". After I do :
"configure --with-pydebug --with-doc-strings --enable-shared
--enable-profiling --enable-ipv6 --with-threads --with-tsc ; make"

The result during make is :
"Failed to find the necessary bits to build these modules:
_dbm                                                  
To find the necessary bits, look in setup.py in detect_modules() for the
module's name."

The release of the dbm library is : 
libgdbm-dev   1.8.3-3  GNU dbm database routines (development files)

The header for dbm : "_gdbmmodule.c" request "gdbm.h", and is here
"/usr/include/gdbm.h"

The "Modules/_dbmmodule.c" use :
#include <gdbm/ndbm.h>" ... #include <ndbm.h> ...
but I have only "/usr/include/gdbm-ndbm.h"

Can you patch the "_dbmmodule.c" to use it ?