Don't know how many of you would want this, but for me it's quite useful. It happens often that I do some testing to determine minimum amount of render samples for a certain batch of renders. If I revisit a project a few months later for a design iteration, it would be nice to know the render settings I used (sometimes I vary them between studios, so it's not like I can simply look at the render window and see what's there from last time).
I don't know if this is info that could be written in exif data somehow?