Will the stimulus plan affect 2008 taxes at all?

This may be a dumb question, but does the stimulus plan about to be signed affect 2008 taxes at all, or just 2009 and future taxes? Is there any reason to delay filing 2008 taxes; more deductions or anything of that sort?

From the IRS website: Tax Provisions in the American Recovery and Reinvestment Act of 2009

The link to the IRS site and to this particular page came from Honesty in this thread he started: Linky