rosmake fails to find rosbuild.cmake on fuerte

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after following the install instructions for Ubuntu 12.04 & ROS fuerte here: http://www.ros.org/wiki/fuerte/Installation/Ubuntu

I'm unable to build any rosbuild-based packages. I receive the following error during "rosmake":

  mkdir -p bin
  cd build && cmake -Wdev -DCMAKE_TOOLCHAIN_FILE=`rospack find rosbuild`/rostoolchain.cmake  ..
  -- The C compiler identification is GNU
  -- The CXX compiler identification is GNU
  -- Check for working C compiler: /usr/bin/gcc
  -- Check for working C compiler: /usr/bin/gcc -- works
  -- Detecting C compiler ABI info
  -- Detecting C compiler ABI info - done
  -- Check for working CXX compiler: /usr/bin/c++
  -- Check for working CXX compiler: /usr/bin/c++ -- works
  -- Detecting CXX compiler ABI info
  -- Detecting CXX compiler ABI info - done
  CMake Error at CMakeLists.txt:2 (include):
    include could not find load file:

      /opt/ros/fuerte/core/rosbuild/rosbuild.cmake

  CMake Error at CMakeLists.txt:4 (rosbuild_init):
    Unknown CMake command "rosbuild_init".

rospack find rosbuild returns:

/opt/ros/fuerte/share/ros/core/rosbuild

so it looks like the /share/ros is missing from all my cmake files. A bug? or am I supposed to do something special with my old CMakeLists.txt files?

I've observed this behavior under both Ubuntu 12.04 (from official debs) and Mac OSX (from source)