I reported this via PM a while back with a savegame and basic description, but I never heard anything back. Evidently, PMs don't do much good to report bugs. So here it is again in the public forum.
You can send a ship anywhere on the map if you land that ship on a planet or a shipyard and launch it from there. For instance, early game, get the 3 free constructors, land them on your homeworld or shipyard. Launch them from there anywhere on the map. When they get out into deep space or find something useful, create a starbase to extend your range. If you want, you can have a colony ship follow one of the constructors and extend your empire to a remote area.
While I haven't used this exploit in a game, I've tested it and abandoned the turns. Can we get this fixed?