It's started here:
http://forums.gentoo.org/viewtopic-t-866955-highlight-.html

Thinkpad x201
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)

kernel 2.6.38-2.6.38.2
x11-drivers/xf86-video-intel-{2.14.0 | 2.14.902} in KVM mode

So, once again, the bug does not appear immediately. A computer boots up normally and xdm starts xorg (both screens runs in lower laptop mode). 
An external monitor becomes flickering red after a login (I use gnome) then a gnome display manager (?) switches monitors to the previous state which is: 
laptop off, external monitor on 

It was working fine with all previous kernels including 2.6.37

emerge --info
Portage 2.1.9.42 (default/linux/x86/10.0/desktop/gnome, gcc-4.4.5, glibc-2.11.3-r0, 2.6.37-gentoo-r3 i686)
=================================================================
System uname: Linux-2.6.37-gentoo-r3-i686-Intel-R-_Core-TM-_i5_CPU_M_520_@_2.40GHz-with-gentoo-2.0.2
Timestamp of tree: Wed, 06 Apr 2011 00:45:01 +0000
app-shells/bash:     4.1_p9
dev-java/java-config: 2.1.11-r3
dev-lang/python:     2.6.6-r2, 3.1.3-r1
dev-util/cmake:      2.8.1-r2
sys-apps/baselayout: 2.0.2
sys-apps/openrc:     0.7.0::pentoo
sys-apps/sandbox:    2.4
sys-devel/autoconf:  2.65-r1
sys-devel/automake:  1.9.6-r3, 1.10.3, 1.11.1
sys-devel/binutils:  2.20.1-r1
sys-devel/gcc:       4.4.5
sys-devel/gcc-config: 1.4.1
sys-devel/libtool:   2.2.10
sys-devel/make:      3.81-r2
virtual/os-headers:  2.6.36.1 (sys-kernel/linux-headers)
ACCEPT_KEYWORDS="x86"
ACCEPT_LICENSE="* -@EULA PUEL AdobeFlash-10.1"
CBUILD="i686-pc-linux-gnu"
CFLAGS="-march=native -O2 -fomit-frame-pointer -pipe"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/eselect/postgresql /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/php/apache2-php5.3/ext-active/ /etc/php/cgi-php5.3/ext-active/ /etc/php/cli-php5.3/ext-active/ /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo"
CXXFLAGS="-march=native -O2 -fomit-frame-pointer -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="assume-digests binpkg-logs distlocks fixlafiles fixpackages news parallel-fetch protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch"
FFLAGS=""
GENTOO_MIRRORS="http://distfiles.gentoo.org"
LANG="C"
LDFLAGS="-Wl,-O1 -Wl,--as-needed"
LINGUAS="en ru"
MAKEOPTS="-j5"
PKGDIR="/usr/portage/packages"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/var/lib/layman/vmware /var/lib/layman/ikelos /usr/local/portage /pentoo"
SYNC="rsync://rsync.sg.gentoo.org/gentoo-portage"
USE="X a52 aac acl acpi alsa avahi bash-completion berkdb branding bzip2 cairo cdr cli consolekit cracklib crypt cxx dbus dri dts dvd dvdr eds emboss encode evo exif fam firefox flac fortran gdbm gdu gif gnome gnome-keyring gstreamer gtk iconv ipv6 java jpeg lcms libnotify mad mikmod mng modules mp3 mp4 mpeg mudflap nautilus ncurses networkmanager nls nptl nptlonly ogg opengl openmp pam pango pcre pdf perl png policykit ppds pppd python qt3support qt4 readline samba sdl session spell ssl startup-notification svg sysfs tcpd tiff truetype udev unicode usb vaapi vorbis x264 x86 xcb xml xorg xv xvid zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1 emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ubx" INPUT_DEVICES="evdev keyboard mouse synaptics" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="en ru" PHP_TARGETS="php5-3" RUBY_TARGETS="ruby18" USERLAND="GNU" VIDEO_CARDS="vesa intel" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" 
Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS