The icons displayed in Quicksilver should be the best available. Currently, it displays a preview icon generated by the QuickLook system, but that's not always better. Some examples:
So what can we do about it?
Again, this could be personal preference, but I think the only time the preview is desirable over the plain icon is for images, PDFs, and videos. If there’s general agreement on that, then option 2 makes the most sense. We should be able to simply check if a file’s UTI conforms to public.image, com.adobe.pdf, or public.movie and enable previews. Disable them otherwise.
We should also provide a way for plug-ins to enable previews for additional types or specific objects. I have some thoughts on implementation, but that can wait.