Education Tax Deduction for All Act of 2008 - Amends the Internal Revenue Code to allow parents of children attending an elementary or secondary school a tax deduction equal to: (1) 25% of their state's average public education per pupil expenditure for each qualifying student attending public school; and (2) 100% of such expenditure for each student attending any other school, including a home school. Allows taxpayers who do not otherwise itemize their tax deductions to claim such deduction.