The new Windows Live Local shows the Earth in 3D. Although it requires to download a 5MB application and it needs a lot of resources, the result is an attempt to emulate Google Earth in a browser. Unfortunately, that browser is Internet Explorer.
You'll be able to see 3D maps only for major cities in the US. But they won't look very nice unless you have a broadband connection and a graphics card that supports Microsoft DirectX 9, with 3D hardware acceleration enabled.
Microsoft did an interesting thing by adding 3D maps into a browser, but they need to improve the performance of their app and the imagery.
Note: to try this, set your regional options in Control Panel to United States and open this site in Internet Explorer. But only if you have Microsoft Windows XP Service Pack 2, Microsoft Windows Server 2003, or Windows Vista.