Shareware author Frank Vercruesse has released DockLock 2.0, a free patch for the Dock that helps it keep its orientation and pinning settings.
DockLock patches the Dock so that it keeps your favorite settings, even after a restart. Version 2.0 doesn’t require the location of the Dock to be restored at login time anymore. And there’s no special installation necessary; just move or copy the file to the desired location and double-click to start it.
DockLock 20 requires Mac OS X v10.0 or later. You can download it (a 77 k file) from Vercruesse’s Web site.