The Tax Policy Center has published an Executive Summary (6 pages), Updated Analysis (59 pages), and Revenue and Distributional Tables (26 tables) for the 2008 presidential candidates tax plans.  From the Executive Summary:

Both John McCain and Barack Obama have proposed tax plans that would substantially increase the national debt over the next ten years, according to a newly updated analysis by the non-partisan Tax Policy Center.

Neither candidate’s plan would significantly increase economic growth unless offset by spending cuts or tax increases that the campaigns have not specified.

Compared to current law, TPC estimates the Obama plan would cut taxes by $2.9 trillion from 2009-2018. McCain would reduce taxes by nearly $4.2 trillion. These projections assume the 2001 and 2003 tax cuts expire in 2010 and that the AMT is fully effective.