The other night I posted up the final logo/description for the 16th "Pre-Fab" title for Project Breakthrough.
It can be seen here:
http://incomics.com - Also, check out the newly released page redesign.

I'm thinking that 16 Pre-Fab titles for creators to choose from, and 4 "Wildcard" slots for creator owned tales would be a nice, even 20 stories. Four stories per "issue", also collected as a big ol' anthology. (See other posts for explanation, price point thoughts, etc.)
Of course, this is malleable. If there ends up being seven creator owned tales that "make it", then of course room would be made. Four is not a written-in-stone number that can never be changed.
By that same token, if for some reason four can't be found (Ha ha) then there are other pre-fabs on deck to swap in. For example, let's say everything's taken, but one of the last people onboard desperately wants to go pre-fab. No problem, time to bring in one of the secret options.

As more material is complete, the InComics.com site will become more filled out, and you'll see more than a short description when you click the various logos.