Don't know if
this helps or not but I'll throw it out there:
Explorer [/n] [/e] [(,)/root,<object>] [/select,<object>]
/n Opens a new single-pane window for the default
selection. This is usually the root of the drive Windows
is installed on. If the window is already open, a
duplicate opens.
/e Opens Windows Explorer in its default view.
/root,<object> Opens a window view of the specified object.
/select,<object> Opens a window view with the specified folder, file or
application selected.
If I get time, I'll see if I get this to show up as a context menu using registry edits. Probably a long shot, but I'll see what I can do.
EDIT: Well I puttered around, in theory you could put a command line here (I did this at lnkfile (.lnk shortcut) level because that seems to be the level at which "Open file location" appears):
HKEY_CLASSES_ROOT\lnkfile\shell\Open &parent of file location\command
So this appears on the menu for shortcuts but I don't know what argument to use for the explorer command line. Problem is I don't know how translate from the .lnk path (which would be assigned to %1 in the command) to the actual target. If I could get that, then string manipulation to get the folder, then add appending \.. to the folder path would probably get me the parent directory.
So I didn't get anywhere but I thought I would report my findings.