Cools! was here...
In a nutshell, the "black box" trading platforms of Goldman and other banks use a combination of proprietary, secret algorithms and the fastest hardware available to take in a torrent of news and other market data and generate a stream of trades that are timed to the millisecond. So, instead of operating on the old stock market adage, "buy on the rumor, sell on the news," a high-frequency trading platform like Goldman's will buy a few milliseconds after the news hits, then sell moments later at a very small premium to other traders and platforms who didn't get the news in (or their trades out) quite as fast. Do this billions of times a day, and voila, you're printing money.
I want you to know that when I read this, I swore at every deity from every religion.