Index tags and stylesheet

Do the gnome stylesheet customizations do anything with the indexing
tags? They don't build an index when I use them on the User Guide. Would
it be possible to get this working? It seems a waste to not create an
index when the necessary tags are all present.

Also, do the yelp stylesheets do anything with the indexing tags? There
is no index for the UG in Yelp - are there any plans to generate one?

Eugene