As mentioned in a comment to https://raspberrypi.stackexchange.com/a/19701/8697 and also in a few other places on this Forum "when the pi is shut down, pulling pin 5 low will make it boot up again"
I can find no reference to this supposed behaviour, although holding this pin low was supposed to boot in safe mode in older versions of Raspbian.
Indeed it does not work on my Pi Model B Revision 2. I can find no mechanism by which it could possibly work. The P6 connector makes the reset function accessible.
Have those proposing this tested this behaviour?