There is a problem with recent kernels (I think to recall 2.6.20 as the first to tail) and Thinkpads wakeup behaviour.
Please read the following problem description twice as many people seem to misunderstand my problem:
After the first (successfully) suspend to disk using swsusp from the vanilla kernel waking up from suspend to ram using the LID button fails. Waking up by pressing the Powerbutton still works.
Even /proc/acpi/wakeup tells LID is enabled for wakeup:
$ cat /proc/acpi/wakeup Device S-state Status Sysfs node LID S3 *enabled SLPB S3 *enabled (...)
It actually is not. There is a small workaround; just disable and reenable LID as wakeup source:
echo LID >/proc/acpi/wakeup echo LID >/proc/acpi/wakeup
And maybe find out why swsusp fiddels with these values. After rebooting wakeup works out of the box
Edit(2007-07-16): Does not work reliable.