It would need to be a recognizable image and symbol. The image would link to the site above, that informs users how you respect their privacy and do not track them. Personally, I'd add it to my sites, because with all the recent concern about privacy, I think my users would appreciate this change, and it would provide some advantage over competing sites. I'd like to visit a site, see that image in the footer, and feel more confident using their service.
I think it would be a good way to encourage change from developers. Very few are going to pull Google Analytics on their own. However, if they get pressure from their users to follow a certain privacy standard, and by doing so they can drop an image on their site to illustrate the change and potentially increase trust and improve their reputation, we might see some improvements.