Update...
I'm exploring one more GTK binding for lua: lgob, by the same author as lgui. It is very 'alpha' now, but much more flexible and complete than lgui. It will be easier to use for older versions of the gnome libraries...
I'll try to do an experimental build soon.
Ref:
http://svn.tuxfamily.org/viewvc.cgi/...vn/lgob/trunk/
EDIT Sat Mar 7 18:25:34 CET 2009: I have a first build running on my Iliad: gtk + dgk