I don't think it will be too popular until the prices come down SOME. At the same place I can get a box of 25 dvd+rw for 10 bucks so you know I wouldn't be using double layer for awhile.
Just browsing CompUSA yesterday. Saw the new dual layer DVD-RW blank disks. Fourteen dollars. Each. One in a box. But the box was nice, same size as a DVD movie box. Must be worth the rest of the money, maybe ten dollars for the box.
I have two Pioneer dual layer drives. But I sure won't be buying dual layer media for a while.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic