Installing Stage

Stage multiple robot simulator
Stage simulates a population of mobile robots moving in and sensing a two-dimensional bitmapped environment. Various sensor models are provided, including sonar, scanning laser rangefinder, pan-tilt-zoom camera with color blob detection and odometry.

Stage devices present a standard Player interface so few or no changes are required to move between simulation and hardware. Many controllers designed in Stage have been demonstrated to work on real robots

from : http://playerstage.sourceforge.net/

Below is what worked for me to install stage.

export CMAKE_INCLUDE_PATH=/opt/local/include
export CMAKE_LIBRARY_PATH=/opt/local/lib

and check this : pkg-config --modversion playercore

if the output is not a version number,try this

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/

now, it should show a version number with the pkg-config --modversion playercore
cakewalk from here:
1. cmake .
2. make
3. make install

cheers!