Great discussion!
One day, I was looking over the shoulder of a local client -- who just happens to have a long, successful, history in both public relations and advertising -- while he checked out my AW. He mentioned that civilians (not artists) "might be positively influenced" by group features, and that, if it were his website, he'd announce each and every one!
I replied that group features were "nice, but really no big deal" and he responded, "To you and other members of this site they may be 'no big deal'. But consumers like success. They love owning things that other people think are desirable. I think you're missing an opportunity, here."
Well, who am I to argue with that? :-)
Since that day, I've used the comments section to announce almost every group feature. (I miss a few if I'm really busy.) It's a way to self-promote without saying, "I think my artwork is awesome!"
Instead, I can say, "XYZ Group thinks my artwork is awesome!" :-)
I've noticed that I pay attention to other artist's Features, too. Not that I believe a Feature means the art is 'better' -- but it does mean that the work has been noticed and highly complimented -- which just might be seen to validate a potential buyer's own opinion.
Also, though I don't really want a dozen or more group badges on my product page (as Bradford mentioned), I do like seeing the variety of groups that choose to Feature one of my images. :-)