The binary files are installed in /opt/ros/fuerte/, so yo will need to include that path when searching for OMPL headers and libs.
The version for the .deb files is of the form X.Y.Z00R, where X.Y.Z is the most recent OMPL release version and R is the revision number in the Mercurial repository for that .deb file.
OMPL in ROS
OMPL is used as a system dependency in ROS, and the correct .deb file is installed automatically as needed.
A ROS package providing the latest version of this library is also available at:
$ svn co https://rice-ros-pkg.svn.sourceforge.net/svnroot/rice-ros-pkg/ompl ompl