For power off via button, init runs "sh /etc/rc shutdown", then sends all processes a SIGHUP, then waits 5 seconds. If there are any processes still alive it'll send SIGTERM and wait another 5 seconds. If any are still alive at that point it'll send'em all SIGKILL and wait another 5 seconds. It'll then tell the kernel to halt the system.
Is there a way to watch this process as it's happening to see where the holdup is? Watching it in general wouldn't be a bad idea. I guess a large part of the issue is not so much that it takes 10 seconds, but that there's no confirmation or indication that it's actually doing anything. It just sits there like it ignored you and you can continue typing at the command line. There's no output or anything until the "syncing disks" line finally pops up.
