Done!

done.js

var Status = Backbone.Model.extend({
    url: '/status'
});

var Statuses = Backbone.Collection.extend({
    model: Status
});

var NewStatusView = Backbone.View.extend({
    events: {
        'submit form': 'addStatus'
    },

    initialize: function() {
        this.collection.on('add', this.clearInput, this);
    },

    addStatus: function(e) {
        e.preventDefault();

        this.collection.add({ text: this.$('textarea').val() });
    },

    clearInput: function() {
        this.$('textarea').val('');
    }
});

var StatusesView = Backbone.View.extend({
    initialize: function() {
        this.collection.on('add', this.appendStatus, this);
    },

    appendStatus: function(status) {
        this.$('ul').append('<li>' + status.get('text') + '</li>');
    }
});

$(document).ready(function() {
    var statuses = new Statuses();
    new NewStatusView({ el: $('#new-status'), collection: statuses });
    new StatusesView({ el: $('#statuses'), collection: statuses });
});