Node.js building a JSON restful web api structure
Sorry if I'm not answering your specific question, but are asking about overall style, or something else?  There's no "right/wrong way" for many things in node.

For example, I would have used http://expressjs.com/ for this:

var express = require('express')
var app = express.createServer()
app.use(express.bodyParser())

app.get('/users', function(req, resp, next) {
   ...
})

app.get('/users/:uid/posts/:pid', function(req, resp, next) {
   ...
})

app.post('/users', function(req, resp, next) {
   ...
})

app.listen(9090)