We're big fans of Meteor as well. Firebase is just a data layer -- we do high-performance, scalable real-time data sync -- but we aren't a complete Framework for building an app. Generally devs will want to use something like Meteor (or Ember, or Backbone, or Spine, etc) to help them organize their code and manipulate the DOM.
In the future we hope to have a Meteor integration, so you can power your Meteor app without running any of your own servers (and do it on a super-low-latency, highly scalable backend).