rosstack is a command-line tool for retrieving information about ROS stacks available on the filesystem. It implements a wide variety of commands ranging from locating ROS stacks in the filesystem, to listing available stacks, to calculating the dependency tree of stacks. It is also used in the ROS build system for calculating build information for stacks.
Prior to Fuerte, rosstack was included in the ros stack. Since Fuerte, it is a standalone tool.
Documentation is available here.