Maybe with the amounts so far, but his MO is to 'take positions' so large they change the fundamentals.
The problem for Soros (and the left in general) is that he underestimates Dubya. Let's face it, at this point George W Bush is practically a force of nature. Soros and his money will no more stand in Bush's way than a billion dollars would stop a hurricane.
My advice to Soros and those like him would be don't waste your money on a fleet of ships that would sail into the face of the gale in order to defeat it. Invest in plywood instead.