Back in 2011, this is the tool stack used by Chicago Tribune.
"This is part one of a five-part series about our recent explorations making choropleth maps using PostGIS, TileMill, Mapnik and Google Maps."
Here is a rundown of the mapbox insfrastrucutre in 2012.
"MapBox is powered by open source, largely by Node.js, Backbone.js, Puppet, and Jekyll, and most of our stack is deployed on Amazon’s high-performance cloud infrastructure."
Infrastrcture aside, this is how the tile rendering itself has progressed.
- Good read & summary: https://github.com/NelsonMinar/vector-river-map#map-of-american-rivers
- d3 vector: http://bl.ocks.org/mbostock/5593150
- mapnik vector tile: http://openstreetmap.us/~migurski/vector-datasource/