Virtual Earth API: Displaying Birdseye Maps With and Without Labels
One of the features added to the Virtual Earth v6.1 Map Control API is the VEMapStyle.BirdseyeHybrid map style. This map style allows you to show the Birdseye map style with street label overlays. If you use the default navigation control in your Virtual Earth application, you can just use the Labels toggle in the navigation control at the top of the screen to switch back and forth between Birdseye and BirdseyeHybrid.
You can also set the map style programatically by calling the SetMapStyle method with the map style:
map.SetMapStyle(VEMapStyle.BirdseyeHybrid); // Show Birdseye with street labels
or
map.SetMapStyle(VEMapStyle.Birdseye); // Show Birdseye without street labels
Here's side-by side screen-shots of the BirdseyeHybrid and Birdseye map styles:


Here's a link to a simple sample page showing how to programatically turn street labels on/off in Birdseye:
Showing Birdseye with Street Labels Sample