Colorbrewer palettes are taken from http://colorbrewer2.org/. They come in three sub-modules grouped by their use:

Colorbrewer maps have an additional attribute and method related to viewing the palettes online. The .colorbrewer2_url attribute is the URL at http://colorbrewer2.org/ at which to view the palette online, and the .colorbrewer2() method will open your browser pointed to that URL.