I think we should remove the following two lines
proc /proc proc defaults 0 0
shm /dev/shm tmpfs nodev,nosuid,noexec 0 0
Because those two line no longer exist in the /etc/fstab file you get during the stage3 installation.
I think it is confusing for users, especially new people.
My two cents
Sorry. This is concerning this section http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=8
Yup, /proc is mounted by openrc's /lib/rc/sh/init.sh whereas the /dev/shm (and other /dev stuff) is done by /etc/init.d/devfs (although I still need to find out where it is actually called)
Ah its a dep from procfs which is in the boot runlevel
Fixed in CVS. Thanks for reporting!