It's quite informal, there's no maths in it at all, but it seems game theory has come up with any number of interesting strategies. Even strategies for when the strategies don't work:
Howard Lederer, broad-shouldered and standing well over six feet, is nicknamed "The Professor" for his studied game and demeanour. When I buttonholed him at the Rio, he told me there were too many bad players around for game theory to be the main asset of a professional. "Pure game theory only comes into play against another great pro in a very pure situation. Basically, it's the psychology of the game. You need to have a feel for the game theory, but psychology trumps game theory: dominating people at their moments of weakness in the tournament, getting to them."
If Lederer is correct, the flood of new players is undermining the usefulness of game theory. Game theory tells you how to avoid losing to perfect play, not how to beat the weak players - known as the fish. The more fish enter the game, the less relevant game theory becomes. The poker legacy of von Neumann may therefore rest with an unusual new breed of players.