I believe this is a good time to improve things like this. Well, I see your point, but on the other hand, it doesn't seem good to me to have two known-different files named "gpl.texi". So if we go that route, I suggest the gnulib file have a different name (gnulib-gpl.texi?).
Also, of course there is the question of updating it. Last time the FSF's address changed (argh), I had to update a lot of different places. I tried to hard to unify the files at that time, so it's hard for me to see them split apart again. Although of course it is not a a frequently changed file, so it's not that big a deal :). I believe the patch below contains all changes mentioned so far. Bruno? Thanks. I'll send that to rms soon (without the node name change). karl