Earlier quoted context omitted.
Bing Maps requires Silverlight for some features. I found that out when I tried Bing recently, but found that Microsoft is more interested in pushing their own technology than pushing their search engine. Microsoft also recently did a project with NASA that requires Silverlight. Thanks, Microsoft.
To be fair, if you wrote a browser plugin like Silverlight, wouldn't you do the majority of your projects in it?
That they're doing this when that means blocking out a huge portion of users on Bing Maps when their main competitor has no such portability problems I think says a great deal about their priorities.