There probably trying to find away to fit phase change in a dual slot cooler
If there going to delay it that much they better launch a whole line with it or NV will kill them with a mid range card out. Even if r600 is all they say it will be not to many can afford it and NV will be on a more mature driver by then with less issues and I'm sure a price drop.
I have been wondering if maybe R600s DX9 performance isn't that great so there holding off till they can show it off in DX10.