Hi,
We recently developed a web resource using Bing Map API to show address as push pin for Custom Entities.
However, we were getting the following notification
The reason being we were using Http version of the API and CRM is on HTTPS. We changed it to use HTTPS version and it fixed the issue.
Else we would have to do the following settings in the browsers
http://du.screenstepslive.com/s/docs/m/7107/l/219447-allow-mixed-content-in-browsers
Helpful post
http://blog.devdave.com/2011/01/removing-mixed-content-warning-when.html
Hope it helps..