The 2012 Indy 500 Parade takes place Saturday afternoon, as it does annually with the 33 drivers serving as honorary grand marshals for the day. The driver with pole position, Ryan Briscoe, takes the rear in accordance with tradition.
The parade will feature 13 floats. Descriptions of them can be found at IndyStar.com.
An explanation of the parade can be found at 500Festival.com:
The IPL 500 Festival Parade allows all spectators to witness the pageantry and larger-than-life floats light up the streets of downtown Indianapolis. Well-known celebrities, costumed characters, marching bands, patriotic units, specialty units, spectacular floats and giant helium balloons will fill the streets to celebrate the world's largest single-day sporting event, the Indianapolis 500®.
The parade has been held in Indianapolis prior to the Indy 500 race every year since 1957, and by now is considered one of the premier annual parades in the nation. Approximately 300,000 spectators are expected.