It was only a matter of time before someone would get their hands on a Radeon HD 3870 X2 and run some benchmarks on it; and once again, it's a Chinese site, this time PCOnline. There are no less than 17 pages of stuff about the card with pictures of it in the nude, and even some power readings, but we'll try to stick to the important bits here.
First of all, yes, it beats the 8800 Ultra hands down in most of the benchmarks, with Crysis and Bioshock being the exclusions, but this is most likely going to be a driver issue with CrossFire not kicking in properly.
As for the default 3DMark06 test, the Radeon HD 3870 X2 managed to produce a score of 18,467, whereas the 8800 Ultra only musters 14,197. Push the resolution up to 2,560x1,600 and the Radeon HD 3870 X2 scores 12,578 versus 8,746 for the 8800 Ultra.
As for the game benchmarks, well, we suggest you take a look for yourself. One interesting thing is the overall PSU load for the system, which measures 303W with the 8800 Ultra and 334W with the Radeon HD 3870 X2. This is not a huge disadvantage, when you consider that you are actually running two cards.
You can find the test
here