soon i will finish this page with information about my debian configuration on my brandnew IBM T40p.
Full ACPI Support (Battery/Temp/CPU...)
agpgart support for dri.sf.net XFree86 driver
Framebuffer and ATI-Xfree86 driver
madwifi with encryption and working /proc/net/wireless
irda (SIR only, FIR will follow someday hopefully)
Suspend to Ram / Supsend to Disk support (2.6.0 linux kernel:/)
USB2.0 external HD
for the impatient people: kernel-conf
Use it with vanilla 2.4.22 and -ac2 patch.
Update: You only need the -ac2 patch if you want to try DRI with the XFree86 DRI Drivers (http://dri.sf.net)
To get the Battery-status working you still have to apply a patch. get acpi-thinkpad-battery-patch. Could be that you have to open a vi session for the rejects.
Giving up and letting go are two different things.