4870x2 will probably be a few ticks faster than 2 4870's as well as a little cheaper. Also by the end of summer prices will have come down a little on both as well Nvidia gpus.
Seems to me that Nvidia is getting too far ahead of themselves. They are making faster products BUT at too high of a consumer price, and in the current global economy many consumers are looking hard at the price tag. Not to mention that MOST non-geeks know of Intel, and many know of ATI through Nintendo, but far less know of Nvidia. Just ask your mom, dad, wife, or gf who they've heard of. Anyway the rift between Nvidia and Intel isn't good, but probably worse for Nvidia because of the non-geek consumers. I like nvidia, ati, intel and amd all the same. I just happen to think that riding against the grain to stand out might not be the best idea in any market right now. I hate to say it but PC upgrades are the least of my expense concerns but if my gpu dies this summer I'd go with a 4850 or 4870 solely on price/performance.