With radeon driver works just fine. After switching to radeonhd driver, X screen looks like color burst or color blending (see attached images). The square on the images is mouse cursor and it is even moving by mouse. I have successfully tried to login blindly to the KDE and have heard startup KDE sound. But screen isn't change. Then I tried to start manually Xorg server on :1 screen with the same result (logs and config are attached).
Gentoo Linux gbox 2.6.35-gentoo #8 SMP Sat Aug 7 17:41:56 EEST 2010 x86_64 Intel(R) Core(TM)2 Duo CPU T5800 @ 2.00GHz GenuineIntel GNU/Linux
ASUS F80S laptop,
ATI Radeon HD 3470,
Intel C2D 2 GHz, 2GB, 250GB
# lspci | grep VGA
01:00.0 VGA compatible controller: ATI Technologies Inc Mobility Radeon HD 3400 Series
# grep DRM /usr/src/linux/.config
# CONFIG_DRM_TDFX is not set
# CONFIG_DRM_R128 is not set
# CONFIG_DRM_MGA is not set
# CONFIG_DRM_VIA is not set
# CONFIG_DRM_SAVAGE is not set
IMG_4409.JPG, IMG_4410.JPG - 2 photos of my screen.
Xorg.0.log, Xorg.1.log - logs of Xorg for :0 and :1 screens respectively.
xorg.conf - my xorg config.
Created attachment 37694 [details]
second photo of my screen
Created attachment 37695 [details]
first photo of my screen
Created attachment 37696 [details]
Xorg log for 0 screen
Created attachment 37697 [details]
Xorg log for 1 screen
Created attachment 37698 [details]
Don't use radeonhd. It's dead.