Is there any question map mashups have gone serious? How about billions of dollars serious? The U.S. website Recovery.gov was built to make transparent the use of economic stimulus money. Now you can track every dollar on a map.
Microsoft has just released a new Silverlight version of Bing Maps that is full of new features and upgrades. Although it's hard to say whether this release of Bing Maps has "stolen the cool crown" from Google, the new features do provide some additional value for users. The "beta" release is not yet available by default, though you can preview the latest version at: http://www.bing.com/maps/explore.