something good for your pocket if you spend 600$ every year just for a gfx card now, is it?
considering the 480 is 500$ whats a measely 100 more?
I actually have the 4890 and wont upgrade until I see any game drop below 30 fps. which means not for a long time. but maybe by then I could get the 9970 for 600!!!!!!!!!!!
Ok, first of all, I never said the 480 is worth its 500$ cost.
Secondly, the 5970 is NOT 600$, its 700$. Thats 200$ difference, which is A LOT. The fact that you know "some places" who sell it for less than its tag price doesnt say much to me, because you might do the same with the 480 and buy it for less.
Thirdly, by 9970, I assume you are joking about the future? Or is it a typo? 
Lastly, Yes your 4890 has enough "horsepower" for today's games. You dont need to upgrade just yet 
If someone wants to buy specifically a Nvidia card (some people just hate ATI) then your only choice is the 470 atm.
I am not saying the 480 is a bad choice, but its price WILL drop pretty fast, and when it does, you will be crying for your lost money. Besides, the fact that it has 1 SM disabled, resulting in 480 cores and NOT its full 512, makes me think of 2 cases:
1. the usual fail-in-production, and the fact that it was late by about 6 months to release, Nvidia HAD to release it as is, with just 480 cores, because a few more months delay would result in losing many loyal customers. and,
2. Nvidia made this whole story up, with the plan to release a 480+ model, like they did with the 260 and 260+ (cores 192 and 216 respectively).
Now I dont know about you, but I am kinda worried that Nvidia might have gone that path, in order to make more money out of basically 1 chip.
But anyway, I wouldnt want a card that reaches 105 Celcius temp, in bencharks, thats like 0 headroom for overclock.
My advice: IF someone wants Nvidia only, wait , just wait.
Now to speak about ATI:
ATI/AMD are some very clever people, because they know that time is money, and they worked their way, taking advantage of Nvidia's "mistake", and released their new series sooner than them. And its new series doesnt consist of just 2 high end expensive cards. Its a full new gfx cards series, which consists of the high end 5970 and 58xx cards, mid end 57xx cards and of course low end cards, which is irrelevant to our case here.
Now the thing is what choices a new buyer has. And Nvidia right now, just doesnt give you any choices, because they were late, and now they are stuck with only 2 high end models.
Its fairly simple, no questions asked, if someone wants a new card and wants to spend from ~100 to 300$, your ONLY choice is ATI. Its as simple as that.
Now, if you want to spend more than 300$, thats were it gets a little complicated.
My 4890 supports physX so I'm sure the 58xx series does as well...Not like many games support that anyway. If you can afford 800 then the ati 5970 is the best if it will fit in your case...Its the fastest and a little cooler then the 480 but will cost 620$.
As for support nvidia does quarterly releases but if there is a problem with a driver you still have to wait a whole quarter for a fix..... Ati doesnt have a set schedule but will move quickly to replace driver updates that have many issues.
No, your ATI doesnt support PhysX, like any ATI doesnt.

And about driver updates, Nvidia is quick to release fixes as well. Just go to their site, click "Download drivers" and you will see what I mean http://www.nvidia.com/Download/index5.aspx?lang=en-us
I can afford $800 what do you recommend morph ?
800$ is A LOT, and you will probably waste your money, but if you DO like to waste money, then I Highly recommend 2 5870's in Crossfire. If you are the type that doesnt want 2 cards, then go for the tough badass that is called 5970, like SwerydAss, very well said.