Oprah Whips Out Giant Stage for Final Shows

5/17/2011 4:30 PM PDT

Oprah Winfrey Whips Out Giant Stage for Final Show at United Center in Chicago

More than 20,000 Oprah Winfrey fans are getting their first look at O's massive pimped out stage as they file into Chicago's United Center for the taping tonight of some of her last few shows.

The arena -- usually home to the Chicago Bulls and Blackhawks -- is packed to the rafters ... according to our spies.

Oprah's A-list friends -- Tom Cruise, John Travolta, and Madonna -- are all expected to hit the enormous two-part stage ... during a taping that could take up to four hours. 

Even Maria Shriver is in Chi-town for the show. Wonder what she has to talk about?