Must admit I can't see how this is any different to the "Request New Content" forum on IS, other than it being much more complicated and not being addressed to a stock-shooting fraternity who understand the technical requirements, etc.
On the IS forum there is a magazine that every month gives out 3 recipes and requests vertical and horizontal shots of each. The 'lucky winner' gets to sell ... er, two images for their trouble. Oh, nearly forgot, they also get a 'credit' and a copy of the magazine too. Invariably the recipes are in tiny niche subjects which are unlikely to get many further sales (apart from the fact that the recipes themselves have all been done to death anyway). It always amazes me how many contributors beaver away in response to the request.
Here's one of the posts. Never in the field of stock photography have so many mushrooms been stuffed (with macadamia) by so many for so few potential sales. Makes me wonder who is getting the greater stuffing __ the mushrooms or the participants?
http://www.istockphoto.com/forum_messages.php?threadid=260401&page=1thats phenomenal, if it wasn't for actually seeing peoples responses I wouldn't have believed anyone would respond. For at least one recipe what they are paying wouldnt cover the cost of ingredients and electricity for me (let alone my time), but oh I'd get a free magazine. Bragging rights of being taken for a ride.