I've got the same kind of error as the above poster I think, on my ThinkPad X41, with gentoo. (I have 915GM chipset.)
I got agpgart, intel chipset support, DRM, I810, i915 in kernel(2.6.13).
I've selected i810 as driver in my xorg.conf, with the PCI buss 0:2:0. (also tried 0:2:1 with same result.)
But when I try to launch X I get the errors:
(WW) I810: No matching Device section for instance (BusID PCI:0:2:1) found
(EE) No Devices detected.
The one about "PCI:0:2:1" I assume is the external monitor device that I'm not intrested in.
The problem is "No Device detected." I realy can't understand why it's not working.
It runs ok with the "vesa" driver but then video playback is horrible, so it's not an permanent option.
Anyone have any ideas how solve this?