Which script mounted /run in Fedora 15?

hi,

i found Fedora 15 has a directory /run, and /var/run is symbol linked to
/run, /var/lock is symbol linked to /run/lock, moreover, /run is mounted as
tmpfs, but it isn't in /etc/fstab, i searched it in /etc but ddin't find any
script do mount it, anybody knows where it is done, why not to do it in
/etc/fstab, thanks in advance.