The Inquirer claims the delay of Windows Vista is giving graphics companies a bit more time to rearrange their GPU roadmaps.
It turns out that the R600 won't be out as early as we all expected. ATI has the flexibility to postpone this chip as there won't be any DirectX 10 API to run the hardware. The original plan was to launch this unified Shader chip in the summer of 2006 but ATI has already informed its partners to be ready for an 80 nanometre die shrink of the R580. The R580+ chip is scheduled for late summer time.
ATI won't release two high end chips within a month or two, so this definitely means that ATI will use the R580+ to provoke Nvidia's G80 and it will launch the R600 later.
There's still not much known about the NVIDIA G80 GPU but it is guesstimated that it will arrive by the end of summer.