Xfastest has links to some screen shots from PCOnline China which look quite authentic, and which are some of the first benchmarks of the upcoming Radeon HD 3870.
They've got screenshots using TechPowerUP's GPU-Z utility showing the details of the Radeon HD 3870 and it looks like the real deal. The GPU is locked at 769MHz with the RAM at 1,197MHz, slightly lower than the reference speeds, but this is quite normal.
The GPU is no hotter than 37 degrees C, so we're not sure why AMD had to design a dual slot cooler for these cards. The test rig was an old Athlon 64 4000+ clocked at 2.9GHz with 2GB of DDR2 memory at 580MHz, so forget about comparing it to anything you've got.
The card scored almost 30,000 in 3DMark03, 14,885 in 3DMark05 and 9,528 in 3DMark06. Not outstanding, but considering the unexciting test platform, these numbers aren't bad.
You can find the screen shots here.