Goldman Sachs is accused of facilitating a hedge fund in the fund's betting against the real estate market. But what hedge funds do, mainly, is short market enthusiasms. (Hence, the word "hedge.") In the case of the real estate bubble, it wasn't mere enthusiasm, it was insanity that inflated the bubble. That is, it was politics, as the easy money policy of the federal government encouraged the banks to make bad loans. So a hedge fund asked GS to build a way for it to short the resulting surge in real estate values, and it did so.
The bubble burst and the hedge fund made money. That's what happens when a hedge fund bets right. But neither the hedge fund nor GS created the real estate related madness. The whole thing was bound to crash. But now GS gets sued. It's a scapegoat. Everyone needs to remember that. Whatever it might have done wrong in the process was really not the problem. The problem was the federal government's policy of making credit for buying real estate available for the asking, abetted by big banks (who simply resold the bad debt to others, with all concerned making fee after fee after fee in the process). And when I say "federal government" I mean Congress and either complicit (in the case of Clinton) or distracted (in the case of Bush) Presidential administrations.
I wish I could have figured out a way to bet against the real estate bubble. We all knew its burst was inevitable. Everyone paying attention knew.