rawhide 20050517, x86_64. ctrl-alt-del is just ignored. Could have sworn it used to trigger a reboot.
In fact, it did. For some reason, getpid() in init is returning 5 which is the pid of a khelper thread, not init itself. Dave -- know of any kernel oddities that could be in play here?
Okay, not the kernel's fault. Booting a U1-ish kernel with my initrd shows the same problem. Swapping to the U1 initrd with the current kernel works fine.
Summary says it all now :)