best i can figure, cyn, the money was created from thin air by way of t-bills.
it's a little hard to say because, for example, there's not a whole lots of real estate on the dept of treasury's website devoted to actual life, particularly not when compared to the amount devoted to neo-liberal horseshit about competition, deregulation and their virtues.
but here's a link to press releases, which of course tell you very little:
U.S. Treasury - Press Releases - September 2008