I don't know if it is configurable, but it's weird default layer doesn't render bus stops, nor a layer selector has been added in map canvas. So, as a temporary solution, I managed to get a Mapnik layer editing file public/javascripts/views/route-stops-view.js
var url = 'http://{s}.tiles.mapbox.com/v3/' + G.config.mapboxKey + '/{z}/{x}/{y}.png'
becomes
var url = 'http://tile.openstreetmap.org/{z}/{x}/{y}.png'
I don't know if it is configurable, but it's weird default layer doesn't render bus stops, nor a layer selector has been added in map canvas. So, as a temporary solution, I managed to get a Mapnik layer editing file public/javascripts/views/route-stops-view.js
var url = 'http://{s}.tiles.mapbox.com/v3/' + G.config.mapboxKey + '/{z}/{x}/{y}.png'becomesvar url = 'http://tile.openstreetmap.org/{z}/{x}/{y}.png'