I was just benchmarking my 5850 Crossfire setup using Vantage and Heaven. I have to say I'm very impressed considering I'm running it in x8x8 Crossfire on an AM2+ DDR2 board. (Don't mind the CPU score, I'm not running OC atm)
3D Mark Vantage - Performance settings: 
Heaven - 1680x1050 - NoAA: 
Heaven - 1680x1050 - 2xAA: 
How did others do? Curious to see what other 5850 Xfire's get on x16x16 and such. As well as 5870's (single and crossfire)