Essentially, it’s a list of DOs and DON’Ts, and some of them may surprise you. In the DO category, they now require you to link back to Flickr whenever you use an image on another site, like your blog. In the DONT category, Flickr says the service is strictly for Photographs… NOT logos, banners, screen-shots, etc… If your account is found to hold primarily non-photohraphic images, it may be suspended.
Some of the new restrictions will be a big bummer for bloggers. I know I have hosted some images for this site on Flickr, that I may have to remove. If you use Flickr, you may want to check out the new guidelines.