For months, the Bing Maps site has been showing off what are essentially embedded mashups. You can search nearby tweets, FourSquare check-ins and other content from partners. Until now, it was merely a showcase of apps either written internally or by a company that Microsoft had blessed. Now, you have the opportunity to get your mashup included on Bing's map.
You can explore the app gallery to see the nearly three dozen map apps Bing already included. Click the Map Apps button in the left pane to see the list. Then learn how to publish to Bing Maps yourself.
To view applications, you need to have Silverlight 4 installed, because that's what Bing Maps uses (the map apps aren't available in "classic" mode). And to develop applications, you need a Windows machine with Visual Studio 2010. Does that feel a little closed? It actually gets worse: each map app will need to be submitted for an approval process before it's available in the gallery.
However, you can test your map app on the live Bing Maps site, as described on the Bing Community blog:
The Bing Map App Test Tool is what you need to test your applications prior to submission to Bing Maps for display and use in the Map Apps Gallery. To use the Bing Map App Test Tool you’ll need to append "?Developer=1" to the Bing Maps URL which will load a specific catalog of Bing Map Apps.
It's not reasonable to expect every map app to go directly in front of millions of users. However, it would be nice to have an open gallery, so you could at least share a map app among friends via a URL.
Despite the approval process, Bing is gunning for great map apps with a contest. The King of Bing Maps Challenge runs between now and August 20, with travel gift cards for the top three apps.