Take a look at this photo (not the one above). It’s a picture of a child prostitute in Congo and it won 3rd place in the category “Contemporary Issues” at the World Press Photo Award 2007. On Flickr it would have been deleted because the child is smoking a cigarette.
Among the responses of Flickr staff in this thread was this gem from Heather: “[…] we as a team can decide if this is something that we want to see on the site […]”. So, basically, the Flickr deal is this: You pay them to host your photos and if they’re something they want to see they won’t delete them. Of course they won’t tell you what they want or don’t want to see. The good news is that no photos of flowers or sunsets have been deleted. Yet.