Steelmesh is a Node.js development / deployment platform that is designed to work in conjuction with systems like CouchDB (i.e. distributed document stores).
Steelmesh has primarily been designed for hosting "behind the firewall" node applications in, dare I say it, enterprise environments. It really hasn't been designed for your next gazillion user startup or other such webscale deployments.
What Steelmesh does do a bang up job on though, is making working with horizontally scaled, homogeneous clusters, really easy. Heck it's almost fun.