I'm sure the admins will reply soon, but I suspect that they have to give all photos the OK before they publish them on their site, just in case any unsavoury characters decide to put up inappropriate material. I am unsure but I think that there is a degree of liability for the web site owner when they publish stuff so if somebody posted something inappropriate then they might be liable - hence giving it a quick check.
The way some sites do things like forums (e.g. this forum) is that when you publish a picture here (rather than the main site), then the picture is actually hosted on some other site and the image embedded into the forum thread. For example, for the the excellent picture on
http://www.discoverwildlife.com/forum/andean-cock-of-the-rock-peru-t11632.html the image itself is actually hosted by
http://img254.imageshack.us/img254/5869/andeancockoftherock01.jpg.
But I'm guessing so expect the truth when the admin get into work Monday.
Ian