Comment 12 for bug 119052

Indeed.

DMI based autoload was only merged lately, in 2.6.23-rc1
(git commits 4f5c791a850e5305a5b1b48d0e4b4de248dc96f9 and b964b437601a0e7d09896d5d9a85c83643e94f41 ).

So thinkpad_acpi autoload won't happen in Gutsy (based on 2.6.22) unless either someone backport this, or add a temporary tweak/hack somewhere to load the thinkpad_acpi module (and to add it in the initrd).