Matt's no stranger to microtransactions, having utilized them back with Iron Realms Entertainment and their many MUD games. His talk with Gamasutra starts out focusing on how microtransactions can generate a very modest income, but mainly center on a small segment of the game's population paying the most to play the game.
Beyond microtransactions, Matt gives a few very interesting details about the development of Earth Eternal and how it reached the form it's in today. Did you know that originally Earth Eternal was going to be a hyper-violent and hyper-sexualized fantasy MMO before it evolved into the playful multi-race animal/fable theme? No? Then you might want to check out the full article, as there's more where that came from regarding the game's evolution.