Google has made some design changes to the map tiles in Google Maps.
There seem to be a lot of subtle changes to map features, including:
Highway shields integrated into the road labels
Changes to the way tunnels are presented
Changes to the highlighting on place names
Changes to land parcels and building outlines
Interestingly Bing Maps also made some changes to their design last week.
I think the design of Bing Maps has improved a lot over the last year but Google Maps still looks much cleaner and more legible to me.
Via: Google LatLong