5970 is actually a really good value if you're going to be shelling out for that level of performance. consider that the 5970 is faster than 2 5850s, for the same price as 2 5850s, and can clock to 5870 performance on each gpu with overclocking and a good non reference cooler design, all for way less than 2 5870s. if you consider that vs the value of 2 5870s, its actually really nice, you're just paying a shit ton for it so its perceived as a bad value, when in fact the 5870 is probably the worst on a price/performance ratio standpoint if raw cost isnt part of the consideration. some people just dont care though, or there's other things that they have to consider. i went for 4 5870s because when i got my first 2, the 5850 and 5970 werent even out yet, and i got my 3rd not originally planning to get a 4th for it, but i wanted something i could potentially CF with the other 2 later down the road, and getting a 5850 didnt really make as much sense, especially since i had the budget for the 5870 lol
ed: the reason you still arent seeing many is because those GPUs they're using are specially binned for their power characteristics. as is the card has a 294w TDP, so if it's not binned exactly right then the card will be outside PCI-e spec and big OEM vendors wont want to use them in their systems. with the yields on TSMC 40nm still not up to par, it makes them hard to make, and it's why most of the cards are priced $100-150 above MSRP
