Protesters against the Iraq war will assemble at noon tomorrow in front of the Democratic Party headquarters at 9th and Figueroa, then march to the federal building via this route:
East on 9th to Broadway. North on Broadway all the way up to Temple. East on Temple to Los Angeles. North on Los Angeles for half a block, for 2nd Rally at Federal Building at Temple and Los Angeles.
Santa Monica's Big Blue Bus has advised riders of possible route changes, but there don't appear to be any preparations on the Los Angeles traffic information page or the MTA website. Here's a link to the organizers.