keyplyr - 9:57 pm on Dec 20, 2012 (gmt 0)

I just spoke with Bing and this is what they said about removing images from their Bing Image Search index:

disallowing files or directories in robots.txt only prevents crawl, not indexation. If you want our system to organically remove these images, you should allow crawl and disallow indexation using a NOINDEX X-Robots-Tag HTTP header.

Several ways of accomplishing this. Since my server is Apache and my images are in several specific directories, I add this to the htaccess in each of those directories:

Header append X-Robots-Tag: noindex