Color2Gray version 2.0.3 is now available and supports InDesign CS6. It allows you to convert placed color photos to grayscale without modifying the original color image. It works best for JPEG and TIFF images.
When outputting in CMYK, the gray image is calculated using a built-in color-to-grayscale conversion in InDesign. The resulting conversion will only render on the black (K) plate. Despite some comments to the contrary, the image is NOT obtained by simply stripping away the color plates; all colors contribute to the final grayscale image.
Keep in mind that Color2Gray is limited by the fact that the user cannot influence the color conversion used. For low-quality newsprint it is often more than sufficient, but you don’t want to use it for high-quality output.
More info and download links: