Sorry it took me an extra day, but yesterday was a bit manic round here

OK, it seems that the instructions you're following are slightly wrong for 64bit .. they tell you to export the wrong path (for 64bit) .. it should have been:
export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig
Here's the FULL instructions for 12.04 64bit (and 11.10 64bit)
If you're running Ubuntu
12.04 64bit install these dependencies:
sudo apt-get install linux-headers-generic autotools-dev build-essential cmake cpp libboost-signals1.46.1 libboost-signals1.46-dev libboost-thread1.46.1 libboost-thread1.46-dev libcv2.3 libcv-dev libgdk-pixbuf2.0-0 libgdk-pixbuf2.0-dev libopencv-features2d-dev libopencv-calib3d-dev libgnomecanvas2-0 libgnomecanvas2-dev libgsl0-dev libgtk2.0-dev libjpeg62-dev libtool libxmu-dev swig python2.7-dev libcv-dev libcvaux-dev libhighgui-dev
ORIf you're running Ubuntu
11.10 64bit install these dependencies instead:
sudo apt-get install linux-headers-generic autotools-dev build-essential cmake cpp libboost-signals1.46.1 libboost-signals1.46-dev libboost-thread1.46.1 libboost-thread1.46-dev libcv2.1 libcv-dev libgdk-pixbuf2.0-0 libgdk-pixbuf2.0-dev libgnomecanvas2-0 libgnomecanvas2-dev libgsl0-dev libgtk2.0-dev libjpeg62-dev libtool libxmu-dev swig python2.7-dev libcv-dev libcvaux-dev libhighgui-dev
OK, now to download Player and Stage -
wget http://sourceforge.net/projects/playerstage/files/Player/3.0.2/player-3.0.2.tar.gz
wget http://sourceforge.net/projects/playerstage/files/Stage/3.2.2/Stage-3.2.2-Source.tar.gz
Now to extract and install Player -
tar -xvf player-3.0.2.tar.gz
mkdir ~/pas/player-3.0.2/build
cd ~/pas/player-3.0.2/build
export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig
export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH
OK, now for Stage -
Install these dependencies (12.04 and 11.10 64bit):
sudo apt-get install freeglut3 freeglut3-dev libfltk1.1 libfltk1.1-dev libltdl7 libltdl-dev libpng12-dev libpng12-0
Now to extract Stage:
tar -xvf Stage-3.2.2-Source.tar.gz
Now you need to edit 3 lines in the CMakeLists.txt file -
gedit ~/pas/Stage-3.2.2-Source/build/CMakeLists.txt
Find the lines that read:-
SET (CMAKE_CXX_FLAG S_RELEASE " -O3 -DNDEBUG ${WALL} " CACHE INTERNAL "C Flags for release" FORCE)
SET (CMAKE_CXX_FLAG S_DEBUG " -ggdb ${WALL} " CACHE INTERNAL "C Flags for debug" FORCE)
SET (CMAKE_CXX_FLAG S_PROFILE " -O3 -ggdb -pg ${WALL} " CACHE INTERNAL "C Flags for profile" FORCE)
and change them to:-
SET (CMAKE_CXX_FLAG S_RELEASE " -O3 -DNDEBUG -Wl,--no-as-needed " CACHE INTERNAL "C Flags for release" FORCE)
SET (CMAKE_CXX_FLAG S_DEBUG " -ggdb -Wl,--no-as-needed " CACHE INTERNAL "C Flags for debug" FORCE)
SET (CMAKE_CXX_FLAG S_PROFILE " -O3 -ggdb -pg -Wl,--no-as-needed " CACHE INTERNAL "C Flags for profile" FORCE)
SAVE the file, and exit gedit.
Back in the terminal run:
mkdir ~/pas/Stage-3.2.2-Source/build
cd ~/pas/Stage-3.2.2-Source/build
And now to test ..
cd ~/pas/Stage-3.2.2-Source/worlds