This is a substantial game-changer in this market. The sub-$15 merchants should use Square over a merchant account. My guess is that square is looking to build

This is a substantial game-changer in this market. The sub-$15 merchants should use Square over a merchant account. My guess is that square is looking to build critical mass but is losing money at the lower end of the spectrum (quick math says on transactions below $6.83), unless they have managed to negotiate a deal with MC/Visa (unlikely).