Select Nodes and/or Comments

Is it possible to allow the module to attach the 'dynamic' signature by Content-Type Node and/or Content-Type Comment?

I'm not sure what the best method would be to enable this, but I'd like users to have signatures in comments attached to nodes (like Quotes or Images) without a signature being included in the original node post. Then comments on an Image would behave just like a comment in a Blog without interfering with display of the posted Image. This feature is especially useful for nodes that are being used in a recent or random block - a signature doesn't make sense in a block.

Image attached of signature in a Quotes block.