I don't think it would be a miniscule market, someone was asking me about multiplayer on iphone the other day and I don't even make iphone games.

Sorry I was unclear. Multiplayer on iOS is a huge market. But with Apple providing peer-to-peer built-in a hosted solution such as PlayRelay might not find many fans. Game Center might be "good enough". That is why I am trying to add things like accountability (opponent is losing and quits the game with no punishment) and tournaments.