rescue --nomount sshpw --username=root sekrit --plaintext url --url http://mirror.eucalyptus/fedora/releases/16/Fedora/x86_64/os/ lang en_US.UTF-8 firewall --enabled --port=22:tcp
Then set up these boot options in your PXE configuration:
ks=http://yourWebServer/ks/fedora-16-rescue.cfg ksdevice=link keymap=us lang=en_US sshd
This works just like rescue mode always has, except you don't need console access. Very cool.
I'm sure this feature isn't news to a lot of Fedora users, but sometimes cool new features like this sneak into a Fedora release and not everyone realizes it, so it seemed to be worth a quick blog.