Google disallowed before 13-11-2011 the embeding of the full website maps.google.com, see thread. It's not working anymore.
So the full website can't be placed in the lightbox anymore. See my demo:
Marker with directions V3
I've tried some possibilities but google doesn't allow to get the full google maps website to be placed in an iframe object. So I'm afraid that it will not be possible anymore to place the google maps website in a lightbox.
See also this thread.