Please look through the mailing list and github. There are at least 5 of these in the works. Off the top of my head: express, vroom, gateway, node-router.
Cool - it was just a "thought". Would love to contribute to something already started.
have you checked out express? Its not fully baked yet, in fact I am working on a fork that uses mustache.js for the rendering. Express puts a nice "sinatra"-esque DSL on top of node.js