Path planning for mobile navigation is typically done by move_base as part of the navigation stack. MoveIt on the other hand is usually used for n-DOF manipulator path planning (including 3D-occupancy maps and collision-avoidance).
So for mobile robots you have a move_base node differentially driving the base to a place (often using SLAM with laser scanners). Once the base goal is done, a trajectory for the 6-/7-axis (multi-)arm is planned in a high dimensional space: 3D-cameras (e.g. stereo pairs, structured light or time-of-flight sensors) perceive the environment and OMPL or similar planners come into place to generate trajectories for the manipulators while the base stands still.