The US government's latest plan (the Public-Private Investment Program) will

help stabilise the economy because it will clear out all the toxic assets in the private banks.
undermine the capacity of fiscal policy to stimulate demand because it is using public funds which could be used elsewhere.
will not impede the capacity of the US Government to create full employment.

Answer: will not impede the capacity of the US Government to create full employment.

Please see the blog US detox lunacy for further information.