This all sounds lovely, the central banks making a sort of heroic stand against ... something. The effect on any currency when that currency's central bank gets involved in this mess will be deflation. Divide $750 trillion in derivatives by $75 trillion in global real estate values and today's dollar will buy you a dime's worth of product after this comes to pass.
Central banks on both sides of the Atlantic are actively engaged in discussions about the feasibility of mass purchases of mortgage-backed securities as a possible solution to the credit crisis.
Such a move would involve the use of public funds to shore up the market in a key financial instrument and restore confidence by ending the current vicious circle of forced sales, falling prices and weakening balance sheets.
Financial Times' coverage of the horrorshow is here