This is nothing but good news for consumers.
As a reference model, I would fully expect this to maintain the current price point of the 7970 while offering generally better performance than the GTX680. Even sweeter would be AMD taking a page out of NV's playbook and "launching" these cards to reviewers (a ghz 7970 and 7950) alongside NV's GTX670 launch.
Lets get these guys undercutting one another so I can buy a new GPU that doesn't cost $350 dollars.
AMD's biggest weakness is their unwillingness to really play ball the way Nvidia does. NV is in the graphics business to win. AMD seems like they're in the graphics business to sell more processors, which makes no sense. This is a step in the right direction. If AMD can release a chip 3 months before Nvidia, then spin on a dime and release a faster revision when challenged, it shows that they're starting to take the game more seriously than they did before.
You've touched on what makes nVidia go. Love him or hate him it's Jen-Hsun Huang (Jensen). It's his company. He's not a hired hand by the board to oversee things. He's passionate about his company. He isn't trying to pocket as much money as possible before his contract is up. The company follows one man's vision. He's an entrepreneur. He also knows as much as anyone about GPU's. I don't approve of many of his business practices, but he's old school. You know where he stands and where you stand with him.
AMD made some decisions that got them terribly in debt. That's something that forces them to be conservative. It also soaks up profits that could go towards R&D and marketing. It's also likely why they embrace open source as much as they do. They let others do the developing they can't afford themselves. If they had the same issues as nVidia had with Fermi and now Kepler they probably wouldn't survive, IMO.
They obviously have terrific engineers in their GPU division. They also seem to have a better grasp on what can and what can't actually be manufactured. Probably because of their connection with GloFo. So, while Jensen is frustrated with TSMC not being able to bring his creations to fruition. AMD probably sits there and wonders exactly what Jensen was thinking when he designs these giant chips. It's easy to say that they are lucky nVidia has all of these issues when transitioning to a new process (or a new Dx, or faster VRAM), but I actually think they make their own luck by understanding the manufacturing better and being able to advance to new technologies better.
To try and get back on topic.
AMD wanted to be first to market. They did what they had to to get there. Judging from the clocks even the first retail cards could reach, they were likely a bit too conservative with Tahiti. nVidia jumped all over it and was able to trump Tahiti. This is in spite of not having their big gun, GK100->110. I'll assume that Rory is at least as smart as I am (joking) and will learn not to take nVidia lightly and only release the best product he can. Once AMD realized the potential for clock speeds on 28nm they should have taken a step back and reloaded the 7970, and by default 7950, at higher clocks. It probably would have only delayed the launch by a few weeks to certify the chips at higher clocks.
If they had done that there would be no gtx 680 right now. The 680 has obviously been released purely to rain on AMD's parade and not allow them to have the entire market to themselves. The lack of supplies shows that GK104 wasn't ready for prime time. It did take the wind out of Tahiti's sails though and make people question purchasing them.
Speculation
Now we have the 670. I think nVidia is releasing the 670 now, because they still don't have enough 680's and yields or wafer starts aren't ramping up fast enough. They need something that they can actually sell in enough volume to generate income. Not just hurt the competition. If they were going to have 680's anytime soon, why would they make the 670 so close in performance? Face it, if performance is as good as these early reviews/leaks have shown, and I believe it is, then how many 680's are they going to sell for $100 more? How many people honestly consider the 7870 at $100 more than the 7850? I think we'll be seeing the same situation with the 670->680. This only makes sense if you don't have any 680's to sell.
I don't know the actual clocks these "new chips" can clock at. if possible AMD should do the 7970-GHz at 1200MHz and a 7950-GHz at whatever it takes to be faster than the 670 (1000MHz-1050MHz?). That won't leave enough space between the 7950 and the 680 for nVidia to squeeze another sku in. This could give AMD the top 2 fastest cards. That would make people sit up and pay attention.
Also
Just to continue on with the strategy of only releasing the best cards possible they need to redo the 7800's too. The 7870's are starting to hit 1300MHz and even 1400MHz. They need to raise the default clocks on those too. nVidia, right now, has no answer for the 7800's. If AMD stands pat and doesn't capitalize on this Rory needs to go back to selling laptops.
Sorry for the wall of text, guys. I work for a company that's also very conservative and I deal with this type of frustration daily. So, you guys just took the brunt of it. I understand that AMD might not be able to do everything I've said here. It's obvious though that they can do more than they are.