Host key signing?

I'm wondering if thought has been put into having `ssh-cert-authority` not only handle signing user keys, but also host keys? A similar challenge exists when one wants to sign host keys to allow for consistent `known_hosts` files. The CA's private key is needed to sign the public keys, and having the private key copied to the hosts is not desirable. The result is needing to copy public keys back and forth, which is part of what this project solves.