Glad this is out, from the Congressional Budget Office:

By contrast, policies that would temporarily increase the aftertax income of people with relatively high income, such as an across-the-board reduction in income taxes or an increase in the exemption amount for the AMT, would have smaller effects because such tax cuts would probably not affect the recipients’ spending significantly.

   In other words, giving very rich people more money is the least effective way of helping the rest of us. Duh.

   Maybe someone should point this out to any of the Democrats who wish to cave on the tax extension fight.