Re: 3x SLI GTX 280 vs. 4870x2 CF
There are none yet since the 4870x2 hasn't officially been launched yet. The only thing we have are a couple of previews and what has been tested with 4870x2's has been limited.
*EDIT* I am mistaken HardOCP, has benchmarks of 4870x2s in Crossfire. But they only tested the 280's in SLi so it will be hard to get an accurate comparison with Tri SLi, especially given the way [H] does their best playable settings benchmarks.