ATI fanboys, your time may have come with the R700-based Radeon HD 4870 X2. It's a US$500 multi-GPU card that basically straps together a pair of Radeon HD 4870s with 2GB of onboard memory to create ATI's fastest single card ever. (It's not your imagination, they're really stepping with the Nvidia-killing, which is sweet.) Benchwise, it actually beats Nvidia's monster GeForce GTX 280 running in SLI in a couple of games, like Age of Conan.
One of the most fundamental changes in the R700 cards—which are two RV770s with a PCI Express switch connecting the the two and double the memory—is that the GPUs actually communicate with each other, whereas past CrossFire configs had both cards basically rendering their own sections independently, then combining them. AnandTech says it's not entirely clear how much communication there will be, but there will definitely be more than there was. Also, the drivers still need to come up to spec to let the card truly shine, but the hardware is totally in the right place. [AnandTech]