Fedora 16 finalized the migration of the system start-up from SysVinit to Systemd. The old commands still work, but as with any other new system, it is recommended that you get used to the new way of doing things. I suspect, eventually, the old commands will get dropped.
If you want to prepare yourself to that day, or if you are just curious about the new way of doing things, Fedora people created a wiki page for you, with a very handy table that shows the old service or chkconfig command, thew new systemctl alternative and a brief description.
I am all for new ways and better software, but on a personal level, I really like “service httpd stop” better than “systemctl stop httpd.service“.