We see that the houses on either side of the Simpsons have changed; Ned Flanders's house on the left has become a geodesic construction. On the right, there's a Chemosphere.
The Chemosphere is the 1960 flying saucer house in the Hollywood Hills by architect John Lautner (wikipedia, Google Earth: 34 7.657 N 118 22.136 W).
As memorably seen in the 1984 Brian De Palma movie BODY DOUBLE:
Probably the most famous photograph of it is by architectural photographer Julius Shulman (1910-2009, wikipedia). Photo from here.
The 2009 documentary about Shulman, VISUAL ACOUSTICS: THE MODERNISM OF JULIUS SHULMAN (Narrated by Dustin Hoffman, came out on DVD in 2010) has some scenes shot in the Chemosphere.
I've just recently gotten around to playing the 2005 PC game GRAND THEFT AUTO: SAN ANDREAS. There's a version of the Chemosphere in the game, so awhile back I tried to take a picture of it in the style of the Julius Shulman photo.
Just taking a picture of the house in the game would be too easy; I wanted to get a guy at the base of the pillar like in Shulman's photograph. This proved difficult; I tried dropping a passenger off in a taxicab, but he wandered over the cliff before I could take the photo. The virtual-Chemosphere really needs a jacuzzi at this area for trapping taxi-cab passengers.
So I got another passenger in the taxi, rolled down the hill until I hit the tree to the left of the Chemosphere's driveway (at which point the passenger got out), then sprinted up the hill to take the photo before the passenger wandered over the cliff. I'm guessing Julius Shulman didn't have to do this when he photographed the Chemosphere.
In the game, I tried to burgle the house (Using the black van and going to the house after 8pm), but it doesn't seem to be one of the burgle-able houses. Which is too bad; it really seems like a great place for the game designers to have hidden an Easter Egg or joke (like a telescope, from BODY DOUBLE). But there doesn't seem to be any way inside the house in the game. Maybe this was for the best; in real life the second owner of the house was murdered by two burglars in 1976.
This isn't the first time the Chemosphere has made an appearance on THE SIMPSONS; in the 1996 episode "A Fish Called Selma", you may remember actor Troy McClure living in it.
(Image from here).