I have an Intel DG956WH motherboard (G965, GMA X3000).  I installed AMD64 Edgy from cd, using an IDE-USB adapter (handy gadget to have around).

 I had my CRT connected to the VGA port through a KVM during the install.  I have since discovered that the KVM doesn't pass DDC signals, which explains my 60Hz refresh rate, and might have something to do with other problems.  (which I maybe should have filed as separate bugs;  let me know if I should split this up.)

 Video worked fine out of the box for me.  Switching to a text console and back screwed up the video, though.  My CRT loses vertical sync, and the screen becomes a flicker of the average colour of whatever is displayed.  (I think the output image is fine, it's just not in a vid mode the monitor can sync to or something.  I can ssh in and use x11vnc -display :0 and continue using my login session, which is how I can compare the displayed image with the colour of the flicker.)

  Upgrading the kernel to linux-image-2.6.19-7-generic 2.6.19-7.11 made switching to a text console safe, but starting a second X server (e.g. with gnome's switch user feature, or presumably with startx -- :1) still screws it up.  With Edgy's 2.6.17 kernel, CTRL+ALT+Backspace to shut down the X server (so gdb restarts it) didn't help.  The restarted X server outputs the same bad video.  (I haven't tested that now because I unwisely started bonnie++ in a gnome-terminal tab on my 500GB WD RE2 hard drive, and it will probably take another 20 hours...)

 Further observations with 2.6.19:  While switched to a text console, x11vnc shows a corner of the screen tiled across the whole 1024x768 .  This doesn't work properly on other machines with other drivers; e.g. nvidia (proprietary) on i386 Edgy.  This probably can't work because the X server can't hold onto the video RAM where the image is if another X server is going to be able to start.

 With 2.6.17 and 2.6.19, glx is a little flaky.
peter@tesla:~$ glxgears 
libGL warning: 3D driver claims to not support visual 0x5a
but it does work.  So do other opengl apps, like xmoto.
(I've attached output of glxinfo).
Sometimes trying to run an opengl program fails, and there's even a kernel log message:
[48096.418558] [drm:i915_cmdbuffer] *ERROR* i915_dispatch_cmdbuffer failed

I'll attach my Xorg.0.log, too.

The splash boot video is kind of corrupted (mostly gray, not full colour), even with 2.6.19.  The difference I saw with switching to tty1 and back might just have been because I took the splash option out of my grub menu.lst before the reboot with the new kernel.  The boot splash is fine with the i386 Edgy CD, but not the amd64 CD.  (unsurprisingly, it's the same booting from the AMD64 CD as with the splash option after the install.)  So I'm booting with a "colour VGA+ 80x25" console.  fbcon and vesafb are loaded, but their use count is zero, and there's nothing the the kernel log about switching to an fb console.  OTOH, the console font does change to a very spindly one after some boot scripts run.  But fbset says no such device opening /dev/fb0, so I guess it's real text mode.  Anyway, booting without the splash fixes VT switching, except for switching between two X servers.  Actually starting the second X server worked ok, just switching back screwed things up.

 I think that's about it.  Xv works.  DDC works when I plug my monitor straight into the mobo.  

  Intel DG965WH boards are pretty nice...  And since it's made by Intel, if the VBE BIOS needs some fixes, they are hopefully actually likely to do something (right?).