I have already mailed one off; I am polishing up the second.
Should be very interesting. I really hope that Morrus will see about putting together a collection of the 10-pagers that didn't make it... I figure it like this:
10 pages per proposal; 10 that get to write those; 7 do not get into the next stage. This means that there will be just shy of 100 pages of untapped material (once you add in some obligatory artwork).
Now, gather those up, pay the authors about $0.02 to $0.04 cents a word for the material to flesh them out to about 25 pages or so. I am guessing, but I figure most (at those rates) would be willing to sell the material in this way.
You could then run a short contest on ENWorld with those 7 proposals, and give the top two a little reward, and ask them to flesh it out to (say...) 75 pages or so.
This would mean you would have:
--- 2x 75-page settings (150 pages)
--- 5x 25-page settings (125 pages)
At 275 pages, you could then talk with one of the d20 publishing houses. Get them to print the material up into a large hard-cover book (or two smaller ones).
Arrange the setting in alphabetical order by author. The exception to this being the two 75 pages, which you put up front. If you go the two book route, place one of the winners in each of the books.
Do an innitial run with an autograph page of the writers and sell them as "special editions" (a-la Ravenloft). Sell those only at ENWorld and at the web site for the house that fronts the printing costs.
After a month or so, release it to the world in stores.
The only thing I cannot figure out right now is a title for the book(s)...