For several months I've seen random flickering on this laptop. I think this started with the switch from EXA to UXA. Now I found a way to reproduce it:

1.) Make sure you are using metacity as wm:
metacity --replace

2.) Make sure you are using compositing:
gconf-editor /apps/metacity/general/compositing_manager

3.) Run a gnome-terminal

4.) Run glxgears

5.) Move the gnome-terminal window so it partly covers the glxgears window.

(Also after trying these steps and toggling compositing in metacity from compositing to non-compositing and back to compositing I've not been able to reproduce it this way anymore, so maybe you need run metacity with compositing as your default wm right from the login)

The flickering should start now and stop as soon as you move the window away again.
As I don't have a camera to capture the flickering I'll try to describe it:
It looks like the whole screen is shifted randomly up and down (not left or right). The cursor gets shifted along with shifted image (different from another flickering issue that got introduced in the 2.6.32 kernel development cycle in which the cursor seems to stay at the same position, but I'm not absolutely sure about that since I haven't seen it this often).

Computer:
Thinkpad R52 1858 69G

lspci:
00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:1c.0 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 1 (rev 03)
00:1c.2 PCI bridge: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) PCI Express Port 3 (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 03)
00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 03)
00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 03)
00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 03)
00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d3)
00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 03)
00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 03)
00:1f.2 IDE interface: Intel Corporation 82801FBM (ICH6M) SATA Controller (rev 03)
00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 03)
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5751M Gigabit Ethernet PCI Express (rev 11)
04:00.0 CardBus bridge: Texas Instruments PCI4510 PC card Cardbus Controller (rev 03)
04:00.1 FireWire (IEEE 1394): Texas Instruments PCI4510 IEEE-1394 Controller (rev 01)
04:02.0 Network controller: Intel Corporation PRO/Wireless 2200BG [Calexico2] Network Connection (rev 05)

Distro:
Ubuntu 10.4 + Xorg edgers repository ( https://launchpad.net/~xorg-edgers/+archive/ppa/+packages?field.name_filter=&field.status_filter=published&field.series_filter=lucid )

xserver-xorg-video-intel:
2:2.9.0+git20091112.dbb68168-0ubuntu0sarvatt

libdrm-intel1:
2.4.15+git20091119.b4312b63-0ubuntu0tormod

xserver-xorg-core:
2:1.7.99.2~git20091111.b5aa2e0a-0ubuntu0sarvatt8

libx11-6:
2:1.3.2~git20091111.54c64267-0ubuntu0sarvatt

linux-image-2.6.32-5-generic:
2.6.32-5.6
(2.6.32-rc8)

mesa:
7.8.0~git20091124.11dce740-0ubuntu0tormod