"Incredibly Shrinking Liquidity" as Goldman Flushed Quant Trading

This is fascinating: "Incredibly Shrinking Liquidity" as Goldman Flushed Quant Trading.

"If ya ain't cheatin', ya ain't tryin'."

Its complex but I think I get most of it.

In short,

1. It appears to be possible for people in the right relationship, to detect the electronic messages that indicate that trades are about to happen on markets such as the NYSE and to make their own trades fast enough to profit from them 
2. Goldman Sachs may be one of the companies in a position to do that
3. GS have regularly been turning $100 million per day in programme trades of this kind
4. GS was the number one such trader
5. Someone has been arrested for stealing their IP
6. GS trades have ceased completely since they discovered that their code was cracked

Someone out there knows the rest of this story. What is it?