Fotonauts will appeal very much to the wikipedia crowd. Like wikipedia, I expect a small minority being responsible in generating most of the content.

In no time, Fotonauts will start attracting the masses in being a reference photo site. Eg. if I want to know more about tattoos, I won't go to Flickr. I just get pictures of tattoos at Flickr. At Fotonauts, I'll get to see the photos and relevant content about tattoos.