I recently added new documentation explaining how to use stylesheets with MapBox, our open source toolset to create custom maps in the cloud, by walking through how we created the DC Nightvision tiles. If you’re interested in creating your own custom maps, this how to will help you get started.
I’ve also packaged up and released everything needed to render and edit the style yourself. The stylesheet was already available on GitHub, but now all the shapefiles — as well as fonts and bitmaps — are available to download in a single zip file. I hope that by having examples like this available we can make the learning process easier and encourage more people to create their own custom MapBox maps.