Just noticed this (2.6.24-rc5-g4af75653):
$ echo 0 > /proc/sys/kernel/nmi_watchdog
$ cat /proc/sys/kernel/nmi_watchdog
1
$ dmesg
[...]
[ 8369.224500] NMI watchdog doesn't know what hardware to touch
full dmesg && config attached
--
Paolo Ornati
Linux 2.6.24-rc5-g4af75653 on x86_64