systemd is a system and service manager, replacement for SysVinit and Upstart. After a six months shift, during which it has been more granularly tested, Fedora 15 brings in, by default, a new system daemon whose code is designed from scratch, with the objective to take the maximum advantage offered by modern Linux kernel.
With systemd, Fedora 15 boots-up faster, particularly on SSD; native systemd service configuration files (or units) are much easier to understand and configure compared to sysvinit scripts, as systemd uses
.service files instead of bash script; all daemons are sorted into their own Linux cgroups, which you may explore beneath
/cgroup/systemd in the file system hierarchy; administrative features of the init system are considerably extended.
Refer to https://fedoraproject.org/wiki/Systemd for more complete information on systemd in Fedora.
Lennart Poettering (lpoetter AT redhat.com)