The problem with competitive technology industries like GPUs is that when you fall behind consistently, you tend to keep falling behind and may even fall further behind. It's just not that easy to suddenly reverse course and switch gears, if you have a bad design, you might be stuck with it awhile. Just look at how long Intel was stuck with P4/Netburst, it took them years to follow up with Core 2. Intel was the dominant market leader and had all the OEMs to themselves, so they could afford to be screwed for years on end and have the time for developing a competitive design.
DAAMIT do not have that luxury. ATI was already the distant 2nd place finisher for 3 generations running (6800, 7800, 8800) mainly because they were so late with a competitive part all 3 generations. Nvidia doesn't have any interest in slowing down and waiting for ATI to catch up, so they are happily developing G90 which is rumored to have 192 SPs and be in the 700-800mhz range in clockspeed at 65nm. Nvidia might even stick with GDDR3 if they can get it up to 1200-1300 (2400-2600 DDR) as the new architecture that started with G80 is not particularly memory bandwidth intensive.
ATI is now in a very deep hole. Their part is highly inefficient and provides very poor performance per watt, especially when you consider that G80 is still at the 90nm process node and still runs cooler and uses less power even though it is a bigger die size than R600. Nvidia has delivered a part with a very innovative design that runs the SPs at a much higher clock than the core, resulting in needing fewer SPs and therefore their transition to 65nm will result in a smaller die than ATI's, improving yields further. Nvidia's part has a very efficient render backend and ROP/TMU design that gives essentially free trilinear and anistropic, which ATI's part is struggling with, and at a higher IQ. ATI also need to fix whatever problems they are having with their ROP/TMU design to bring MSAA back on board where it should be, instead of sapping performance by being done in shaders.
Overall Nvidia is in a very good position, as they pretty much hit every performance and IQ goal they had with the G80 design. ATI has a lot of work to do at the drawing board, which will result in further delays and put them further behind. At this point they might not have the R6x0 refresh part out before Nvidia has an entire new generation out in G90, and being a whole generation behind could be a deathblow for DAAMIT as they are also struggling to get Barcelona out and have it be competitive with Penryn.
The big advantage that R600 theoretically had over G80 was the enormous shader transistor budget. G90 is rumored to have a ton of shader power increase over G80 if the 192 SP thing is to be believed, which will negate the only big theoretical advantage R600 had outside of the completely unnecessary and probably expensive excess memory bandwidth. R600 is so much weaker than G80 in basic rendering design such as geometry setup, actual fillrate (even though the 512-bit memory bus and 1024-bit ring bus gives it a massive theoretical advantage), texture filtering, and AA that it's almost unbelievable that DAAMIT would have released it in the state it got released in except that we know that DAAMIT was already 6 months late and had to get something, anything out the door, plus financially DAAMIT is staring into the abyss.
Nvidia designed a powerful, efficient, balanced architecture with G80 and they can easily ride it for the next 2 years just with die shrinks and slapping more SPs onto it and clocking it into the stratosphere. ATI is in a big hole here, not unlike the big hole AMD is staring at with Barcelona versus Penryn, and they need to do something and it needs to be miraculous if they want to catch up with Nvidia now. Being a whole generation behind is the worst thing imaginable in the technology industry.