There are benchmark results for a 670 and 680 posted here:
http://www.refractivesoftware.com/forum ... f=9&t=7383 (towards the end)
Does anyone have a GTX 670?
I own a 670 myself (not for octane performance however). I get about the same numbers as posted in the benchmark topic above.
Justix is right that it doesn't perform as good as a 470.
These cards are designed quite differently and it may be the case that they will never perform as good in octanerender as the 500 or 400 series.
In my personal opinion these are great gaming cards - but they obviously don't do so well for GPGPU applications.
Having said that - i'm sure much will be (and is being) done to get as much as possible out of them.
One biggest things is the power needed by the card, less than previous card, so less temperature... so less noise too

.
Yup i can confirm that!
My 670 runs pretty quiet and cool, even under full load it sits in the low 60's (deg. C). and the fans sit at about 40% (i have the gigabyte windforce edition with 3 fans on it).
NVidia are definately out for performance per watt and they have done it... I think the 470 uses about 215W at full load, a 670 is spec'ed at 170W.
Along with that and the increase memory capacity I quite like them, even tho they aren't lightning quick in octanerender.
Cheers
Chris.