I received a note from Google today indicating that Google Desktop 2 is coming out of beta with several enhancements. As part of that, there's a Maps plug-in for Sidebar:
This new Sidebar panel rotates through maps relevant to the user€™s location and interests. Like most features in the Sidebar, the panel is auto personalized and does not require input from the user unless they€™d like to customize the display. In addition to maps based on the user€™s activity and location, the map rotation also includes maps of popular locations around the world such as Paris, Hong Kong, and Cairo.
Here's more from Google's Blog.
So between the new Yahoo! Maps, Google Local/Maps and Virtual Earth (and all the developers) we should have a very interesting set of tools and map-based applications coming in the next few quarters.