These guys have well worked-out equations and algorithms that can reliably predict what the market will do (at the moment), but they don't know why they work. They just know they work. The problem with that is that it means that they don't know if they're facilitating just trades that increase wealth, or whether they're taking advantage of unintended consequences of the system as we have it.
It could be possible, I suppose, that they've very thoroughly analyzed each part of the market and have all the just-trade possibilities worked out in their heads and they're doing nothing but facilitating just trades. But if that's the case, fire Tim Geithner and put these guys to work. They apparently know what to do with the market.
But I will bet a silk pajama that they've got Darwinian algorithms and fancy equations that are busy exploring the possible solution spaces for market trades, but they have no freaking clue what any of those solutions actually means or whether it represents a just trade. And given the history of the last 6 months and what has come to light about our financial system, I think these guys are almost certainly taking advantage of unintended consequences of our system, unintended consequences that (since they were unintended) actually represent grave injustice. And by "grave injustice" I don't mean that they're going into the inner city and stealing money from welfare mothers. I mean mean their trades cause people to think there's money when there isn't, which ends up being the same thing.