The design website Core77 has an interesting article by Willem Van Lancker, a Google Map User Experience and Visual Designer, called Google Maps: Designing the Modern Atlas.
Google Maps' design evolution 2009 (top) - 2011 (bottom)
The article looks at the cartographic design decisions that have gone into creating Google Maps. Willem explains the historical design changes that Google Maps has undergone as well as examining the problems of trying to create a universal design that also reflects the needs and design expectations of regional users.
Localised coloration in the roadways of Tokyo, London, & Paris and 3d buildings in Seattle