I saw the announcement about page-count being added to the \paper{}
possibilities and I was thrilled to see it as I had been wanting just
exactly that. I've found that it does not work within \layout{}. Other
things like system-count seem to be working with a \layout{} block but
page-count doesn't. Is this to be expected, or should it also work in
\layout{} as well? It would certainly be useful for controlling page
counts in numerous scores being typeset together.