I just added a new JsonBodyParser middleware to floor. I think it's usage is pretty straight forward:

    #[deriving(Decodable, Encodable)]
    pub struct Person {
        pub firstname: String,
        pub lastname:  String,
    } 

    let mut server = Floor::new();
    server.utilize(Floor::json_body_parser();

    fn post_handler (request: &Request, response: &mut Response) { 
        let person = request.json_as::<Person>().unwrap();
        let text = format!("Hello {} {}", person.firstname, person.lastname);
        response.send(text.as_slice()); 
   };

   server.post("/a/post/request", post_handler);

    curl 'http://localhost:6767/a/post/request' -H 'Content-Type: application/json;charset=UTF-8'  --data-binary $'{ "firstname": "John","lastname": "Connor" }'

Repository: https://github.com/floor-org/floor