In Zombieland, the survivors of the zombie apocalypse camp out at the L.A. mansion of a famous actor (who plays himself in the film). The house used for the scenes actually belongs to RHOA's Kim's "Big Poppa" Lee Najjar.
I immediately recognized the grand stairway in the foyer (the previous image) from the episode of Teen Cribs that featured Najjar's home, and a tour given by two of his children. It looks as if all the exteriors and interiors were shot in his home. (The top images are from Zombieland and the bottom are from Teen Cribs.)