bit-tech.net | Nvidia GeForce GTX480 & GTX470
NVIDIA’s GeForce GTX 480 and GTX 470: 6 Months Late, Was It Worth the Wait?
NVIDIA GeForce GTX 480 GF100 DX11 Video Card Review
NVIDIA Fermi - GTX 470 - GTX 480 - GTX 480 SLI Review
Nvidia GeForce GTX 480 Review: Fermi Arrives

Performance-wise, the GTX480 seems to be 10-15% better than a HD5870-1GB and GTX470 seems to be roughly similar to an HD5850. But price/noise/heat/power are all favouring the ATi cards significantly and the ATi HD5970 still has the lead by about 30-35% (according to Tweakers.net), so nVidia may need to tweak their cards a bit more.

ATI has already announced 2GB versions of the HD5870, which might make up the difference a little according to AnandTech. It's also possible they'll put out a higher clocked card against the GTX480.

To me, the Fermi cards were more hype than substance. They played it out to be the ATi killer and while it does have better performance, 10-15% over the already amazing performance of the 5870 is minimal at best. Technically by the numbers its a better card, however the average [intelligent] gamer not out to flaunt their e-peen doesn't care about the extra 7-15 frames per second in a handful of games when they're already exceeding their monitors refresh rate by at least 25%.

ATi's eyefinity seems to be striking some hits among the high end users with multiple monitors as they seem to enjoy the experience at least once. ATi also has the single card performance crown until the dual GPU Fermi card comes out, but none of that seems to really matter to the enthusiasts or the companies' bottom lines. I'm fully expecting ATi to come with a slightly revised card just as they did with their 4890 (their fastest single chip of the previous generation) and at least match the GTX480's performance or beat it at a lower price.

nVidia seems to be banking too much on GPGPU abilities rather than what their product was initially intended for; gaming. They keep flaunting their PhysX and Tesselation abilities, however only benchmarks and a couple of [endorsed] games support these features that do not make a significant difference. ATi/AMD have it right in making games look better and deliver more performance for the newest titles to the gamers. nVidia is also content with its possibly decades old philosophy of making a monolithic chip resulting in lower yields before revising the architecture and making it efficient.

When ATi released their 5870 and 5850, everyone and their dog claimed it was a paper launch due to lack of availability (which was confused with high demand), so I am also claiming paper launch for the GTX 480 and 470; TSMC announced they are still producing nVidia's chips at less than 50% yield and no doubt these cards will be in high demand as they are the latest and greatest available.

ATi has a technology lead right now and seems to be on a roll; nVidia will have a tough time catching up if they decide to stay in the discreet gaming graphics sector (which is contrary to what they want to do). My next graphics card will be a 5870 or 5890 despite whatever nVidia has to offer because of business practices, and value for my 500 or so dollars.

AND ANOTHER THING:
These cards are 10-15% (at best depending on resolution and testing site) faster over ATi's reference model cards which have already been overclocked and modified by companies such as sapphire. They have also added better coolers to get away from thermal meltdown limits as well as voltage and overclocking tweaks. Crysis seems to be loading up the 480 to just under boiling temps on air. You cannot argue overclocking the green team's card as it is right up against the PCIe electrical limits (around 300 watts) and 96 degrees Celsius is more than I want any computer component to get. There isn't much overclocking room considering thermals and electricals.