Steps to reproduce:
1. Download gconfmm-2.6 from SVN trunk or use gconfmm-2.6-devel provided with Fedora 7
2. Type ./autogen.sh
3. Type make


Stack trace:
Making all in tools
make[1]: Entering directory `/home/axelgenus/temp/gconfmm/tools'
Making all in extra_defs_gen
make[2]: Entering directory `/home/axelgenus/temp/gconfmm/tools/extra_defs_gen'
g++ -DHAVE_CONFIG_H -I. -I../../gconf -DORBIT2=1 -pthread -I/usr/include/sigc++-2.0 -I/usr/lib/sigc++-2.0/include -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/gconf/2 -I/usr/include/orbit-2.0 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include      -g -O2 -MT generate_defs_gconf.o -MD -MP -MF .deps/generate_defs_gconf.Tpo -c -o generate_defs_gconf.o generate_defs_gconf.cc
mv -f .deps/generate_defs_gconf.Tpo .deps/generate_defs_gconf.Po
/bin/sh ../../libtool --tag=CXX   --mode=link g++  -g -O2   -o generate_extra_defs generate_defs_gconf.o  -pthread -L/usr/lib -lglibmm-2.4 -lsigc-2.0 -lgconf-2 -lORBit-2 -lgthread-2.0 -lrt -lgobject-2.0 -lglib-2.0   -lglibmm_generate_extra_defs-2.4
mkdir .libs
g++ -g -O2 -o generate_extra_defs generate_defs_gconf.o -pthread  -L/usr/lib -lglibmm-2.4 -lsigc-2.0 -lgconf-2 -lORBit-2 -lgthread-2.0 -lrt -lgobject-2.0 -lglib-2.0 -lglibmm_generate_extra_defs-2.4  
/usr/bin/ld: skipping incompatible /usr/lib/libsigc-2.0.so when searching for -lsigc-2.0
/usr/bin/ld: skipping incompatible /usr/lib/libgconf-2.so when searching for -lgconf-2
/usr/bin/ld: skipping incompatible /usr/lib/libORBit-2.so when searching for -lORBit-2
/usr/bin/ld: skipping incompatible /usr/lib/libgthread-2.0.so when searching for -lgthread-2.0
/usr/bin/ld: skipping incompatible /usr/lib/librt.so when searching for -lrt
/usr/bin/ld: skipping incompatible /usr/lib/librt.a when searching for -lrt
/usr/bin/ld: skipping incompatible /usr/lib/libgobject-2.0.so when searching for -lgobject-2.0
/usr/bin/ld: skipping incompatible /usr/lib/libglib-2.0.so when searching for -lglib-2.0
/usr/bin/ld: skipping incompatible /usr/lib/libm.so when searching for -lm
/usr/bin/ld: skipping incompatible /usr/lib/libm.a when searching for -lm
/usr/bin/ld: skipping incompatible /usr/lib/libpthread.so when searching for -lpthread
/usr/bin/ld: skipping incompatible /usr/lib/libpthread.a when searching for -lpthread
/usr/bin/ld: skipping incompatible /usr/lib/libc.so when searching for -lc
/usr/bin/ld: skipping incompatible /usr/lib/libc.a when searching for -lc
make[2]: Leaving directory `/home/axelgenus/temp/gconfmm/tools/extra_defs_gen'
Making all in m4
make[2]: Entering directory `/home/axelgenus/temp/gconfmm/tools/m4'
make[2]: Nothing to be done for `all'.
make[2]: Leaving directory `/home/axelgenus/temp/gconfmm/tools/m4'
make[2]: Entering directory `/home/axelgenus/temp/gconfmm/tools'
make[2]: Nothing to be done for `all-am'.
make[2]: Leaving directory `/home/axelgenus/temp/gconfmm/tools'
make[1]: Leaving directory `/home/axelgenus/temp/gconfmm/tools'
Making all in gconf
make[1]: Entering directory `/home/axelgenus/temp/gconfmm/gconf'
make  all-recursive
make[2]: Entering directory `/home/axelgenus/temp/gconfmm/gconf'
Making all in src
make[3]: Entering directory `/home/axelgenus/temp/gconfmm/gconf/src'
make[3]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf/src'
Making all in gconfmm
make[3]: Entering directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm'
Making all in private
make[4]: Entering directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm/private'
make[4]: Nothing to be done for `all'.
make[4]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm/private'
make[4]: Entering directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm'
/bin/sh ../../libtool --tag=CXX   --mode=compile g++ -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gconfmm\"  -I../../gconf -I../../gconf -DORBIT2=1 -pthread -I/usr/include/sigc++-2.0 -I/usr/lib/sigc++-2.0/include -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/gconf/2 -I/usr/include/orbit-2.0 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include    -g -O2 -MT client.lo -MD -MP -MF .deps/client.Tpo -c -o client.lo client.cc
mkdir .libs
 g++ -DHAVE_CONFIG_H -DG_LOG_DOMAIN=\"gconfmm\" -I../../gconf -I../../gconf -DORBIT2=1 -pthread -I/usr/include/sigc++-2.0 -I/usr/lib/sigc++-2.0/include -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/gconf/2 -I/usr/include/orbit-2.0 -I/usr/include/glibmm-2.4 -I/usr/lib64/glibmm-2.4/include -g -O2 -MT client.lo -MD -MP -MF .deps/client.Tpo -c client.cc  -fPIC -DPIC -o .libs/client.o
../../gconf/gconfmm/client.h: In static member function 'static int Gnome::Conf::BasicTypeTraits<int>::to_cpp_type(int*)':
../../gconf/gconfmm/client.h:259: error: cast from 'int*' to 'gint' loses precision
../../gconf/gconfmm/client.h: In static member function 'static bool Gnome::Conf::BasicTypeTraits<bool>::to_cpp_type(gboolean*)':
../../gconf/gconfmm/client.h:290: error: cast from 'gboolean*' to 'gint' loses precision
client.cc: In member function 'GSList* Gnome::Conf::Client::get_list(const Glib::ustring&, GConfValueType) const':
client.cc:238: error: cast from 'void*' to 'gint' loses precision
make[4]: *** [client.lo] Error 1
make[4]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf/gconfmm'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/axelgenus/temp/gconfmm/gconf'

Other information:
I can't compile also simple programs using the gconfmm-2.6-devel package provided by the OS.

// main.cc (thanks to ZeFlunk of the Linkage team)
#include <gconfmm.h>



int main(int argc, char *argv[]) {

  Gnome::Conf::init();

  Glib::RefPtr<Gnome::Conf::Client> client = Gnome::Conf::Client::get_default_client();



  return 0;

}

$ g++ -o gconfmm-test main.cc `pkg-config --libs --cflags gconfmm-2.6`
/usr/include/gconfmm-2.6/gconfmm/client.h: In static member function ‘static int Gnome::Conf::BasicTypeTraits<int>::to_cpp_type(int*)’:
/usr/include/gconfmm-2.6/gconfmm/client.h:259: error: cast from ‘int*’ to ‘gint’ loses precision
/usr/include/gconfmm-2.6/gconfmm/client.h: In static member function ‘static bool Gnome::Conf::BasicTypeTraits<bool>::to_cpp_type(gboolean*)’:
/usr/include/gconfmm-2.6/gconfmm/client.h:290: error: cast from ‘gboolean*’ to ‘gint’ loses precision

It seems the same problem. :(