There are no current competitors. There's MPEx, and there's various attempts to recreate GLBSE. These compete among themselves for the "most-GLBSE alike" title, and when they don't do that they negotiate to reunite into one single unity of fail, thus actually recreating their model.

Outside of that pretend competition (as you can't really compete when there's no actual difference) there's no such thing as competition going on in BTC finance land: the play exchanges and MPEx couldn't compete if they wanted to, as they serve entirely disjunct markets. The random noob that started this thread for his literary-financial & fiducial new media etc project being a convenient point in case.

I suppose at most you could say the competition is cultural, in the sense of sanity trying to compete with firm conviction. That's hardly any sort of competition either.